Thyroid carcinoma of the pyramidal lobe: A narrative review of reported cases

Abstract

Papillary thyroid carcinoma arising from the pyramidal lobe is a rare entity that poses diagnostic and therapeutic challenges, as this anatomical structure is frequently overlooked during preoperative assessment and thyroid surgery, potentially compromising oncological outcomes. A narrative review of the literature identified 38 reported cases of pyramidal lobe thyroid carcinoma, of which 29 cases, including one additional illustrative case, met predefined inclusion criteria and were analyzed. Extracted data included demographic characteristics, clinical presentation, thyroid function, imaging and biopsy methods, operative management, histopathological findings, tumor multifocality, extrathyroidal extension, tumor-node-metastasis staging, adjuvant treatment, and follow-up. Most tumors were papillary carcinomas occurring predominantly in female patients, commonly presenting as anterior neck masses with preserved thyroid function. Ultrasound and computed tomography were the most frequently utilized imaging modalities, while fine-needle aspiration was the primary diagnostic tool. Surgery most often involved total thyroidectomy with central or combined central and lateral neck dissections. Multifocality and extrathyroidal extension were reported in a substantial proportion of cases. Follow-up data were limited, with no documented recurrences among reported cases. Awareness of the pyramidal lobe as a potential primary site of thyroid carcinoma and its complete surgical excision are essential for optimal oncological management.

Key Words: Pyramidal lobe; Thyroid cancer; Cervical lymphadenopathy; Thyroidectomy; Papillary thyroid carcinoma

Core Tip: Thyroid carcinoma arising from the pyramidal lobe is an uncommon but clinically significant entity. This review synthesizes all reported cases to date and highlights key diagnostic challenges, patterns of lymphatic spread, and surgical considerations unique to pyramidal lobe malignancies. By integrating a rare illustrative case with a comprehensive narrative review, this article underscores unresolved issues in detection and management, emphasizes the oncologic importance of complete pyramidal lobe excision, and outlines directions for improving preoperative assessment and long-term disease control.

INTRODUCTION

Thyroid carcinoma is the most prevalent endocrine malignancy worldwide, with incidence rates varying across different demographics. In the United States, the incidence of thyroid cancer has nearly tripled since 1975, from 4.9 to 14.3 per 100000 individuals. This increase is primarily due to papillary thyroid carcinoma (PTC), the most common form representing 80% of cases[1]. Thyroid cancer occurs more frequently in women than in men, with the incidence of PTC in females being 2.6 times higher than in males[2]. PTC is the most common malignancy affecting the pyramidal lobe of the thyroid gland[3].

The pyramidal lobe of the thyroid gland is an anatomical variant that arises from incomplete involution of the thyroglossal duct and is typically located beneath the hyoid bone[4]. It is a common feature observed in approximately 38%-60% of individuals in European populations[5,6]. Despite its frequency, the pyramidal lobe is often underrecognized during routine ultrasound examinations and may be excluded from preoperative evaluations[7,8]. The pyramidal lobe can be affected by the same pathologies as the rest of the thyroid and although rare, primary carcinoma arising in the pyramidal lobe may exhibit aggressive behavior, including local invasion and lymphatic metastasis[3,9]. Even more uncommon is the occurrence of pyramidal lobe-dominant PTC, which may present either as a solitary tumor confined to the pyramidal lobe or as the largest tumor focus within a multifocal thyroid cancer[3,10,11]. Consequently, the clinical and pathophysiological characteristics of this condition are poorly understood[11]. Inadequate identification and excision of the pyramidal lobe during thyroidectomy can lead to residual malignant tissue, thereby elevating the risk of disease recurrence and compromising therapeutic outcomes[12,13]. Given that the presence of the pyramidal lobe can complicate the surgical approach, accurate recognition and complete removal are critical. Failure to detect and excise this lobe, particularly when it harbors PTC, not only increases the risk of postoperative complications, but may also diminish the effectiveness of adjuvant therapies such as radioactive iodine (RAI) treatment[14]. Furthermore, even in the absence of carcinoma, incomplete removal of this lobe may interfere with serum thyroglobulin (TG) levels in follow-up assessments[15].

In this paper, we report a rare case of PTC presenting with supraclavicular lymphadenopathy and originating as a solitary tumor in the pyramidal lobe. By presenting a thorough literature review, we stress the need to increase awareness of pyramidal lobe PTC and its diagnostic and therapeutic implications.

CASE REPORT

Our case involves a 22-year-old woman who was referred to our department for total thyroidectomy. At the time of referral, the patient had a four-year history of cervical lymphadenopathy. During the initial investigation, ultrasonography (US) revealed four enlarged lymph nodes in the right supraclavicular region (d = 9.5-17 mm), reactive lymphadenopathy around the jugular vessels, and an otherwise normal thyroid gland, except for a small nodule (d ≤ 2 mm) in the right lower lobe. Computed tomography (CT) of the chest and neck showed an enhanced entity in the anterior upper mediastinum with microcalcifications, an enlarged right subclavicular lymph node (d = 10 mm), and enhanced lymph nodes near the lower-right border of the thyroid. Magnetic resonance imaging (MRI) of the neck complicated the differential diagnosis, suggesting that the aforementioned enlarged lymph nodes, located supraclavicularly, were nodules of ectopic thymic tissue. Approximately three years later, an open biopsy of the largest nodule, located near the sternal notch, revealed a lymph node with metastatic PTC. Following prolonged diagnostic evaluation, the metastatic lymph nodes were suspected to have originated from a PTC in the right lower lobe, a burnt-out thyroid tumor, or an ectopic thyroid tumor near the hyoid bone. Despite cervical lymphadenopathy being present at the initial evaluation, the prolonged diagnostic course, driven by the benign-appearing imaging findings, young age, and coronavirus disease 2019 restrictions, might have contributed to the extent of nodal disease at the time of surgical evaluation.

The patient was later referred to our surgical department for further evaluation. Clinical examination revealed palpable nodules in the right supraclavicular and infrahyoid regions. Preoperative assessment of the thyroid showed no significant findings (thyroid stimulation hormone: 0.4 μIU/m, calcium: 9.4 mg/dL, phosphorus: 3.4 mg/dL, parathyroid hormone: 36 pg/mL). Given her medical history, a total thyroidectomy was scheduled, along with radical central (levels VI-VII) and right lateral (IIa, III, IV, and Vb) lymph node dissection. The surgery lasted four hours without complications. The entire thyroid gland, including its pyramidal lobe, as well as the lymph nodes at the specified levels were removed (Figure 1). Both recurrent laryngeal nerves were identified using intermittent intraoperative nerve monitoring. Her postoperative recovery was uneventful; she was discharged two days after surgery and was supplemented with calcium and vitamin D for transient hypoparathyroidism.

Figure 1 Surgical specimen showing extensive central (VI, VII) and right lateral (IIA, III, IV, VB) lymph node dissection (left) and the resected thyroid gland (right).

The pathology report confirmed the presence of follicular variant PTC originating from the pyramidal lobe (d = 7 mm), with its extension confined to the thyroid parenchyma (Figure 2). Of the 35 lymph nodes extracted, only 4 were found to be metastatic, all located between the neck muscles (levels IV-VI). The remaining gland showed signs consistent with a nodular colloid goiter. Additionally, parts of a parathyroid gland and thymic tissue were found in the excised tissues.

Figure 2 Histopathology specimen of papillary thyroid carcinoma of the pyramidal lobe.

During follow-up, her voice, which had been hoarse after the operation, returned to normal within a month. At the most recent follow-up, 20 months after surgery, the patient remains disease-free following RAI therapy and negative I¹³¹ scintigraphy, with ongoing biannual US surveillance.

LITERATURE REVIEWS

Thyroid carcinoma arising from the pyramidal lobe is a rare entity with diverse clinical manifestations, posing diagnostic challenges and is usually treated by harnessing extensive oncologic operative techniques. We systematically searched PubMed/MEDLINE, Web of Science and Science Direct for articles containing the keywords “pyramidal lobe”, “thyroid cancer”, “papillary cancer” and “recurrence” in combinations with Boolean operators. We included only cases of primary pyramidal lobe carcinomas, meaning thyroid cancers explicitly located in the pyramidal lobe or, in cases of multifocality, the largest tumor is found in the pyramidal lobe. The reason for this approach was that cases in which the pyramidal lobe lesion represented an incidental or smaller focus within a multifocal disease pattern likely reflect intrathyroidal extension from another site rather than a true primary pyramidal lobe carcinoma[11]. Studies referring to carcinomas involving the thyroglossal duct or developing inside the relevant cyst were excluded, due to the significant differences in tissue pathology. Cases describing recurrent disease or reoperation in which the primary tumor origin could not be clearly attributed to the pyramidal lobe were excluded.

Common characteristics among the above reports included sex, age, clinical features, thyroid function, imaging, biopsy methods, initial diagnosis, operative procedure, histopathology report, multifocality, extrathyroidal extension, tumor-node-metastasis (TNM) staging, RAI treatment postoperatively and follow-up. Articles were excluded if more than half of the fourteen predefined data elements required for descriptive synthesis and included in the summary table were missing. The percentages measured in each category contained patients in whom the above characteristics were explicitly mentioned. The appropriate classification was extrapolated from the tumor description and cytology or biopsy report in the case studies but only for the TNM and biopsy staging categories.

LITERATURE DISCUSSION

A total of 38 cases were found in the literature but only 29, including our own, fulfilled the aforementioned criteria and were included in this study.

Ten of the patients (34.5%) were described by Yoon et al[11], three (10.3%) by Santrac et al[10] and more recently, two (6.9%) by Papavramidis et al[16]. The average age of the patients was 28 years (range, 21-77 years) and there was a clear female predilection (89.7% female, 10.3% male).

Clinical features included lymphadenopathy (4%), neck mass or swelling (52%), no signs or symptoms (4%) and others (8%) such as difficulty swallowing, neck pain and unintentional weight loss. Thyroid function was normal in most cases (95.2%) and only one report mentioned hyperthyroidism (4.8%) due to Graves’ disease.

Imaging included a combination of methods: US was used in more than half of the cases (54.2%), followed by CT (41.7%), MRI (12.5%) and scintigraphy (4.2%). Preoperative biopsies involved thyroid (isthmus, right or left lobe) or lymph node open biopsy in only a few cases (10.5%), most reported a cytology or biopsy of the suspicious pyramidal lobe using fine needle aspiration (68.4%) and some cases did not require a biopsy at all (21.1%). We deemed the initial diagnosis to be the one considered after all investigations were concluded.

Thyroidectomy (93.1%) was the predominant choice of treatment, including subtotal and total thyroid removal, whereas very few cases followed a targeted approach (6.9%), removing only the affected site of the pyramidal lobe. Lymph node dissection was performed in most patients (65.5%). Central neck dissection, either therapeutic or prophylactic, was the sole method for lymph node management in half of the cases (52.6%), with the other half proceeding with a more radical approach of central and lateral neck dissection (42.1%).

Although all cases were diagnosed as thyroid carcinoma prior to surgery, the histology varied. Preoperatively, most cases were defined as PTC (61.5%), followed by follicular and medullary carcinomas, each accounting for 7.7%, while the remaining 23.1% comprised other less common types of thyroid cancer. With regard to final histopathology, only the report by Ogawa et al[17] mentioned a follicular carcinoma of the pyramidal lobe (3.5%) in the report. PTC (86.2%) was the diagnosis concluded from the rest of the reports, with a handful identifying a papillary microcarcinoma (10.3%) of the pyramidal lobe.

Multifocality was defined as the presence of tumor foci in areas other than the pyramidal lobe, such as the isthmus and the right and left thyroid lobes. This characteristic was found in nearly equal proportions across the studies, with the multifocal pattern being the least prevalent (41.4%). Extrathyroidal extension involves the infiltration of the tumor beyond the capsule towards the surrounding muscles and fibroadipose tissue[18]. This feature was observed in approximately half of the patients (51.7%). Most tumors were characterized as either stage T1 (≤ 2 cm in diameter, 44%) or stage T3 (> 4 cm or invading the surrounding strap muscles, 40%). Equal frequency was noted between stages T2 (> 2 cm and ≤ 4 cm limited to the thyroid, 8%) and T4 (extrathyroidal extension into major neck structures, 8%)[19].

Lymph node involvement was identified in almost every other case (56%). Regional metastases predominantly affected the central lymph nodes (CLN) with or without lateral lymph node (LLN) involvement. However, there were a few instances of skip metastasis patterns, where metastatic lymph nodes were found solely in the lateral compartment. Data regarding the use of RAI as a prophylactic or supplemental treatment postoperatively were minimal and inconsistent with TNM staging, indicating a more personalized approach for each case. Out of the reports that provided such information, more than half proceeded with the use of RAI (60%). Finally, although only a minority of cases included follow-up data in their report, no recurrences were noted.

DISCUSSION ABOUT PYRAMIDAL LOBE THYROID CARCINOMA

Although the pyramidal lobe is a frequent anatomical variation, it is oftentimes overlooked in clinical practice owing to imaging restrictions. It is however noteworthy to point out that a careful examination of this lobe is particularly important especially in the context of thyroid malignancies[20].

The diagnosis of carcinomas in the pyramidal lobe presents several challenges. Firstly, this lobe may not be consistently visualized using conventional imaging modalities such as ultrasound, because of its variable size and anatomical position[6]. In one study, Freilinger et al[6] reported that the sensitivity of high-resolution ultrasound varied significantly depending on the examiner’s experience, with sensitivities of 85.0% and 42.5% for two different operators, respectively. This variability highlights the difficulty in detecting the pyramidal lobe, particularly in clinical settings where operator expertise may differ. In comparison, CT demonstrated higher sensitivity and specificity; however, it is not routinely used in all patients with thyroid pathology[7,21]. Scintigraphy is also suboptimal for visualizing the PL, as it is designed for functional rather than morphological imaging of the thyroid[20]. Additionally, fine-needle aspiration biopsy may be technically challenging because of the inconsistent location and limited accessibility of the lobe. Given these limitations, a high index of suspicion and comprehensive imaging evaluation are essential, particularly in patients with known or suspected thyroid cancer.

Pyramidal lobe carcinoma can present with regional lymph node enlargement, further complicating the differential diagnosis. Possible benign diagnoses for this condition include reactive or hyperplastic lymph nodes, ectopic thyroid tissue or remnants of the thyroglossal duct, and various forms of thyroiditis, which are discussed in further detail. Hyperplastic or reactive lymph nodes may appear enlarged because of infection, inflammation, or autoimmune conditions such as Hashimoto’s thyroiditis[22]. On ultrasound, these nodes typically exhibit an ovoid shape, preserved hilum, lack of microcalcifications, and low vascularity[23]. Thyroid ectopia or a thyroglossal duct remnant can also mimic metastatic disease on imaging, often demonstrating features such as continuity with the thyroid gland and lack of typical lymph node features[24]. Thyroiditis, including Hashimoto’s, De Quervain’s, and Riedel’s, can cause nodular lesions with increased fluorodeoxyglucose uptake on positron emission tomography (PET)-CT, mimicking neoplasia, while the presence of anti-thyroid peroxidase and anti-TG antibodies aids in the diagnosis[25,26]. Malignant etiologies include thyroid lymphoma, anaplastic thyroid carcinoma, medullary thyroid carcinoma, and metastatic disease from primary tumors outside the thyroid. Thyroid lymphoma is often associated with Hashimoto thyroiditis and is characterized by a rapid increase in gland size and involvement of cervical lymph nodes. Diagnosis typically involves fine-needle aspiration biopsy followed by immunohistochemical analysis using markers such as CD20 and CD5. Anaplastic thyroid carcinoma is highly aggressive, with rapid spread to the cervical and mediastinal lymph nodes, and appears sonographically as a heterogeneous, hypervascular mass without calcifications. Histologically, it lacks the Orphan Annie nuclei alterations observed in papillary carcinoma[26]. Medullary thyroid carcinoma causes lymph node metastases but has a different cellular origin (C cells), with the diagnosis relying on elevated calcitonin and carcinoembryonic antigen measurements[25]. Secondary metastases from other tumors, such as lung, kidney, breast cancer, and melanoma, can also mimic PTC, with PET-CT and histopathological examination being essential for diagnosis[26].

Another important differential diagnosis is thyroglossal duct cystic carcinoma (TDCC). Although both pyramidal lobe PTC (PLTC) and TDCC originate from cells sharing common embryological origins, they represent distinct clinical entities. While PLTC arises from functional thyroid tissue with preserved follicular differentiation, TDCC originates within cystic epithelial remnants of the thyroglossal duct and is characterized by cyst wall architecture rather than organized thyroid parenchyma[27]. As a result, the distinction between PLTC and TDCC is primarily based on anatomical and histopathological criteria, rather than molecular or biochemical features. In order to maintain clinicopathological homogeneity, even though they usually present as PTC, TDCC cases were excluded from this review.

Biochemical biomarkers are key in diagnosing and monitoring of differentiated thyroid cancer, yet data regarding their specificity in pyramidal lobe PTC are limited. Like intrathyroidal PTC, pyramidal lobe PTC is expected to secrete TG. The available literature does not provide specific data assessing TG characteristics in pyramidal lobe PTC, including potential TG isoform differences or post-translational modifications such as glycosylation patterns. Regarding biochemical markers conferring increased risk of metastatic disease, there is lack of evidence correlating metastatic tendency to overexpression of matrix metalloproteinases, vascular endothelial growth factor, and other invasion- and angiogenesis-associated molecules. Thus, the observed metastatic behavior of pyramidal lobe PTC is more plausible attributable to diagnostic delays and anatomic proximities.

Several cases of pyramidal lobe thyroid cancer have been described in the literature with the majority consisting of PTC. Isolated reports describe medullary thyroid carcinoma with concurrent papillary microcarcinoma and a single case of follicular carcinoma involving the pyramidal lobe. Most patients presented with some degree of anterior neck enlargement, swelling, or palpable mass. To the best of our knowledge, our case is the first to describe metastatic lymphadenopathy occurring nearly four years prior to the histological confirmation of pyramidal lobe PTC. We also consider the young age at disease onset equally noteworthy, given the rarity of pyramidal lobe PTC in individuals younger than 21 years[17].

Early presentation with lymphadenopathy raises concerns about unusually aggressive PTC behavior. Several factors in our case may have contributed to this phenotype. First, younger age at diagnosis is a known risk factor for lymph node involvement; patients under 45 years of age have been shown to have a significantly increased risk (odds ratio = 1.52) of nodal metastasis[28]. The association between younger age at PTC diagnosis and aggressive behavior at the molecular and biochemical level has not been established. Furthermore, pathological examination revealed focal lymphovascular invasion, which is a well-established risk factor for locoregional dissemination[29].

Whether pyramidal lobe PTC represents a distinct biological and molecular entity or reflects conventional PTC developing in thyroid tissue, remains poorly elucidated. In a case series by Yoon et al[11], 70% of pyramidal lobe–dominant PTCs were positive for the BRAF V600E mutation, suggesting that these tumors share common molecular features with conventional PTC. In line with thyroid carcinoma, specific genomic alterations have been shown to confer a higher risk of aggressive metastatic behavior, including early lymph node involvement. Chromosomal rearrangements affecting RET and resulting in fusions with genes belonging to the PTC cluster (e.g., PTC1, PTC3) are strongly associated with lymph node dissemination, especially in younger patients. In addition, TERT promoter alterations are linked to more aggressive PTC behavior, although this effect is more pronounced in older individuals. Finally, the BRAF V600E mutation may also contribute to lymph node metastasis, especially when coinciding with TERT promoter mutations, forming a co-mutational signature that carries a higher cumulative risk of aggressive biological behavior[30].

Pyramidal lobe PTC has significant surgical and therapeutic implications, affecting both disease recurrence and treatment outcomes. As a common anatomical variation and remnant of the thyroglossal duct, the pyramidal lobe can be frequently disregarded during total thyroidectomy, leading to residual disease that may in turn undermine treatment efficacy[12]. Given the increased prevalence of CLN metastasis in pyramidal lobe PTC[11], careful preoperative evaluation is warranted, and prophylactic CLN dissection (CLND) may be considered in select patients. Pyramidal lobe lymphatic drainage, like the rest of the gland, initially involves the perithyroidal lymph nodes; therefore, special consideration should be given to possible CLN metastasis in cases of pyramidal lobe carcinomas. It has been suggested that malignancies involving the Delphian node can predict the presence of disease in the central compartment thus indicating the need for a CLND. In addition, CLN metastasis is more frequently observed in patients with LLN involvement. This suggests that lateral neck dissection (LND) might be unnecessary if sentinel or CLN are negative, with the exemption of cases in which LLN involvement is verified either clinically or by US[10]. Our case encompassed lymph node metastasis to the central (VI) and lateral (IV) compartments, a feature probably attributed to anatomical proximity[31]. A possible explanation for the increased lymph node dissemination prevalence is that the pyramidal lobe as an anatomic region is frequently overlooked in routine ultrasound assessments, leading to diagnosis delays. The preferred surgical approach consists of extended total thyroidectomy with pyramidal lobectomy[14]. In cases where a pyramidal lobe carcinoma is biopsy-proven after total thyroidectomy, complementary pyramidal lobectomy is required to achieve adequate regional control.

Regarding RAI treatment, iodine metabolism and sodium iodide transported expression is directly correlated to RAI efficacy[32]. Although downregulation of sodium iodide symporter (NIS) is known to confer RAI resistance, there is a lack of literature evidence supporting anatomical location-specific implications of this effect, such as pyramidal lobe PTC. In the future, focused studies assessing NIS expression levels and RAI outcomes in PLTC may further inform personalized therapeutic strategies. Table 1 provides a summary of the shared characteristics of all cases documented in the literature[33-39].

Table 1 Summary of cases of pyramidal lobe carcinoma.

Ref.	Sex	Age	Clinical features	Thyroid function	Imaging	Pre-op biopsy	Initial diagnosis	Operation	Pathology	Multifocality	Extrathyroidal extension	TNM	RAI	Follow-up
Ogawa et al[17]	F	21	Neck enlargement	Normal	US: Isoechoic encapsulated mass (40.3 mm × 27 mm × 17.6 mm) in the pyramidal lobe. CT: Hypoattenuated mass adjacent to pyramidal lobe. 201Tl Scintigraphy: Uptake from nodule with dilution at washout	FNAB: IIIb	Follicular cancer	Isthmusectomy, pyramidal lobe excision and prelaryngeal lymphadenectomy	Minimally invasive follicular carcinoma of the pyramidal lobe (35 mm)	No	Invasion of capsule and nearby blood vessels	NA	NA	Well-after 15 months
Kim et al[33]	F	54	Neck mass	NA	US: 30 mm mass of mixed echogenicity, with microcalcifications, extending from submental area to thyroid cartilage, abnormal lymph nodes in levels IV (R), III (L), and IV (L). CT: Dumbbell shaped mass with cystic and solid components, expanding to right isthmus of thyroid gland	FNA: VI	Papillary cancer with lymph node metastasis in levels IV (R) and III (L)	Total thyroidectomy with central and bilateral modified, radical neck dissection	Papillary carcinoma of the pyramidal lobe (15 mm). Bilateral lymph node metastasis	No	Strap muscle involvement	NA	NA	NA
Santrac et al[10]	F	36	NA	NA	NA	No	NA	Total thyroidectomy with central neck dissection, sentinel lymph node biopsies bilaterally (III/IV levels)	Papillary carcinoma of the pyramidal lobe (12 mm). Colloid nodular goiter	No	No	pT1bN0M0	No	Well-after 18 months
Santrac et al[10]	F	41	NA	NA	NA	FNAB: VI	Papillary thyroid cancer	Total thyroidectomy with central neck dissection, sentinel lymph node biopsies bilaterally (III/IV levels)	Papillary carcinoma of the pyramidal lobe (20 mm). Hashimoto thyroiditis	No	No	pT1bN0M0	No	Well-after 18 months
Santrac et al[10]	F	22	NA	NA	NA	FNAB: III	NA	Total thyroidectomy with central neck dissection, sentinel lymph node biopsies bilaterally (III/IV levels)	Papillary carcinoma of the pyramidal lobe (15 mm). Delphian lymph node metastasis. Hashimoto thyroiditis	No	No	pT1bN1M0	Yes	Well-after 18 months
Ha et al[23]	F	48	Normal	Normal	US: Suspiciously malignant nodules in pyramidal lobe (4.1 mm) and right mid-lobe (3.6 mm), a hypoechoic nodule in the left mid-lobe (2 mm)	FNAB: VI (from right mid-lobe)	Thyroid malignancy	Total thyroidectomy with central lymph node dissection	Papillary thyroid microcarcinomas-pyramidal lobe, right lobe and left lobe	Yes	No	pT1aN0M0	No	Well-at recent follow-up
Wagner et al[34]	F	62	Neck mass, swelling, weight loss	Normal	US: Large submental mass with heterogeneity. CT: Mass located superiorly to thyroid isthmus, destroying hyoid bone, left submandibular lymph node (15 mm)	FNAB: VI	Papillary thyroid cancer	Total thyroidectomy with en bloc resection of tumor element, skeletal muscle, hyoid bone, central lymph node dissection and left radical neck dissection (II/III/IV)	Tall cell variant of papillary carcinoma of the pyramidal lobe (65 mm). Metastatic lateral lymph node	No	Infiltration of nearby soft, fibroadipose tissue, skeletal muscle and hyoid bone-multiple pulmonary nodules bilaterally (< 10 mm)	NA	Yes	NA
Ritterhouse et al[25]	F	24	Neck mass	Normal	US and CT: Irregular, lobulated, hypervascular mass arising from pyramidal lobe	Open biopsy: Papillary thyroid carcinoma	Papillary thyroid cancer	Total thyroidectomy with central and lateral neck dissection, en bloc resection of tumor overlying strap muscle and wedge resection of left thyroid lamina and cricothyroid membrane	Solid variant papillary carcinoma of the pyramidal lobe (37 mm). Metastatic central and left compartment lymph nodes with extranodal extension. PTC of the right thyroid lobe (2 mm)	Yes	Skeletal muscle and cricothyroid membrane involvement	pT4aN1bM0	Yes	Well-after 14 days
Yoon et al[11]	F/M: 8/2	58 ± 12.5	NA	NA	NA	NA	NA	8/10 patients: Total thyroidectomy, 2/10 completion thyroidectomy, 3/10 central lymph node dissection, 2/10 modified radical neck dissection	Papillary thyroid carcinoma of the pyramidal lobe	5/10	8/10	T1: 2/10, T2: 0, T3: 7/10, T4: 1. N0: 5/10, N1a: 3/10, N1b: 2/10	NA	No recurrence at follow-up
Papavramidis et al[16]	F	43	Difficulty swallowing, cervical pain	Normal	US: Hyperechoic nodules in left (n = 3) and right (n = 2) thyroid lobe, hypoechoic submandibular mass. CT: Round mass above the hyoid bone. MRI: Heterogeneous mass above the hyoid bone, right lobe mass and multiple swollen lymph nodes (d ≤ 12 mm)	FNA: VI	Papillary thyroid cancer	Total thyroidectomy	Papillary thyroid carcinoma of the pyramidal lobe (14 mm), PTC in right thyroid lobe (3 mm)	Yes	No	pT1bN0M0	NA	NA
Papavramidis et al[16]	F	73	Neck swelling	Normal	CT: Pyramidal lobe mass	No	Undifferentiated carcinoma of the pyramidal lobe	Total thyroidectomy with central and bi-lateral neck dissection	Papillary thyroid carcinoma of the pyramidal lobe (50 mm). Metastasis of central and lateral lymph nodes in levels III (R) and II (L). Multiple papillary microcarcinomas in left and right thyroid lobe	Yes	Focal extension	pT3N1bM0	NA	NA
Petris et al[22]	F	50	Neck mass	Hyperthyroidism	MRI: Expansive tumoral mass, adjacent to hyoid bone	No	NA	Tumor excision and Sistrunk procedure followed by total thyroidectomy with central lymph node dissection	Solid and sclerosant variant papillary thyroid carcinoma of the pyramidal lobe, PTC in thyroid isthmus	Yes	Invasion of capsule, infiltration of adjacent fibroadipose and muscular tissue	pT3N0M0	Yes	NA
Kang et al[35]	F	52	Neck mass	NA	US: Anterior neck mass and hypoechoic nodule in left thyroid lobe. CT: Solid mass with cystic and calcified components	FNAC: VI	Thyroglossal duct or ectopic thyroid carcinoma	Sistrunk and lobectomy of left thyroid lobe with central lymph node dissection	Papillary thyroid carcinoma of the pyramidal lobe (30 mm). Metastatic lymph nodes. PTC in left thyroid lobe (5 mm)	Yes	No	pT2N1aM0	NA	NA
Pinto et al[36]	F	38	Neck swelling, compression symptoms	Normal	US: Multinodular goiter with large nodule in left thyroid lobe	FNAC: II	NA	Total thyroidectomy (excision of pyramidal lobe and tubercle of Zuckerkandl)	Papillary microcarcinoma of the pyramidal lobe (2.5 mm)	No	No	pT1aN0M0	No	NA
Messias et al[3]	F	77	Neck mass	Normal	US and CT: Thyroid nodules in pyramidal (largest) and right thyroid lobe	FNAC: VI	Papillary thyroid cancer	Total thyroidectomy en block with pyramidal lobe and hyoid bone, central lymph node dissection	Papillary thyroid carcinoma of the pyramidal lobe (25 mm). Metastatic central lymph nodes	Yes	RLN invasion (R)	pT3bN1aM0	Yes	Well-after 6 months
Own Case	F	22	Lymphadenopathy	Normal	US: Suspicious nodule in right lower lobe, normal pyramidal lobe, multiple pathological lymph nodes. CT: Hyperattunuated enlarged lymph nodes nearby thyroid lower right lobe, enhanced entity in anterior upper mediastinum. MRI: Ectopic thymic tissue above suprasternal notch and supraclavicularly (R)	Lymph node open biopsy: Metastatic papillary thyroid carcinoma	PTC in right lower lobe or burnt out primary tumor or ectopic thyroid tissue and metastatic lymph nodes	Total thyroidectomy with radical central and right lateral neck dissection	Papillary thyroid carcinoma of the pyramidal lobe (7 mm). Metastatic intermuscular lymph nodes (IV-VI)	No	No	pT1aN1M0	Yes	Well-after 20 months
Ren et al[37]	F	21	Neck mass	NA	US: Large entity with distinct borders in anterior neck. CT: Soft tissue mass anterior to thyroid cartillage	No	NA	Right thyroid lobectomy with isthmus resection, central lymph node dissection and modified zone I dissection	Papillary thyroid carcinoma of the pyramidal lobe (30 mm). Metastatic central lymph nodes in level I	No	No	pT1N1M0	NA	Well-after 5 years
Mao et al[38]	F	32	Neck mass	NA	US: Solid-cystic mixed nodule with calcification in pyramidal lobe	FNA: VI	Papillary thyroid cancer	Pyramidal lobe resection	Papillary thyroid carcinoma of the pyramidal lobe	No	No	T1bN1aM0	NA	NA
Hage et al[9]	F	33	Neck swelling	Normal	US: Large mixed solid-cystic nodule between left lobe and isthmus with calcifications, smaller nodule nearby	FNA: III	NA	Left hemithyroidectomy followed by completion thyroidectomy with central lymph node dissection	Papillary carcinoma of the pyramidal lobe (30 mm). Metastatic peri-thyroid lymph nodes	No	No	pT2N1M0	NA	NA
Pathak et al[39]	M	27	Neck swelling	Normal	NA	FNAC: Medullary carcinoma (right lobe)	Medullary Cancer	Total thyroidectomy with central and right radical lymph node dissection	Medullary carcinoma of the right lobe and isthmus with extrathyroid extension. Papillary microcarcinoma of the pyramidal lobe. Metastatic lymph nodes (medullary-central and lateral, papillary-central)	No	No	NA	NA	NA

TNM: Tumor-node-metastasis; RAI: Radioactive iodine; F: Female; US: Ultrasound; CT: Computed tomography; FNAB: Fine-needle aspiration biopsy; NA: Not available; 201Tl: Thallium-201; R: Right; L: Left; FNA: Fine-needle aspiration; PTC: Papillary thyroid carcinoma; M: Male; MRI: Magnetic resonance imaging; FNAC: Fine-needle aspiration cytology; RLN: Recurrent laryngeal nerve.

CONCLUSION

The pyramidal lobe, although often considered a minor anatomical variation, has significant implications for the diagnosis and management of thyroid carcinoma. Surgeons and clinicians must be vigilant regarding its potential involvement in malignancies to optimize surgical outcomes and long-term disease control. Future reports should focus on including parameters that facilitate a better understanding of the long-term behavior of pyramidal lobe primary tumors, such as duration of follow-up, RAI administration, thyroglobulin levels and recurrence status.