Primary arteriovenous malformation of the eyelid mimicking a dermoid cyst: A case report

Abstract

BACKGROUND

Arteriovenous malformations (AVMs) of the eyelid are rare vascular lesions that can be difficult to diagnose because they often present in unusual ways. While AVMs typically show signs of vascularity such as pulsation, bruit, or skin discoloration, some lesions may appear as simple painless eyelid swellings and closely resemble benign conditions like dermoid or epidermal inclusion cysts. Such atypical presentations can lead to misdiagnosis and unexpected challenges during surgery.

CASE SUMMARY

We report an atypical case of an AVM presenting as a cystic eyelid mass. An 18-year-old female presented with a progressively enlarging swelling of the left upper eyelid over a period of two years. Non-contrast computed tomography revealed a well-defined soft-tissue lesion, provisionally diagnosed as an epidermal inclusion cyst. The patient underwent excisional biopsy under general anesthesia. A greyish-brown mass was completely excised and submitted for histopathological examination, which confirmed the diagnosis of an AVM. The postoperative course was uneventful, and no recurrence was observed at one year of follow-up. This case highlights the variability in the clinical presentation of AVMs.

CONCLUSION

This case highlights how an eyelid AVM can closely mimic a benign cystic lesion such as a dermoid cyst, creating a significant diagnostic challenge. Even in the absence of obvious vascular signs, vascular malformations should be considered in atypical or progressively enlarging eyelid masses. Early recognition and careful surgical management can help prevent complications and achieve excellent cosmetic and functional outcomes.

Key Words: Arteriovenous malformations eyelid; Vascular malformations; Computed tomography; Excisional biopsy; Case report

Core Tip: Arteriovenous malformations (AVMs) of the eyelid are rare and may mimic benign cystic lesions, leading to misdiagnosis. This case highlights an unusual presentation of AVM as a presumed epidermal inclusion cyst on imaging. Complete surgical excision with histopathological confirmation remains essential for accurate diagnosis and management. Clinicians should maintain a high index of suspicion for vascular malformations in atypical eyelid masses to avoid intraoperative complications and ensure appropriate treatment.

INTRODUCTION

Arteriovenous malformations (AVMs) are rare congenital vascular anomalies characterized by direct communication between arteries and veins without an intervening capillary network, resulting in high-flow vascular channels[1]. Orbital and periocular AVMs are particularly uncommon and represent a small subset of extra cranial vascular malformations. Although congenital in origin, these lesions may remain clinically silent for years and present later in adolescence or early adulthood due to hormonal influences, trauma, or spontaneous progression[1,2]. The clinical presentation of eyelid AVMs is highly variable. Classical features include pulsatility, bruit, and compressibility; however, many cases lack these findings and instead present as slowly enlarging, non-specific masses. Such atypical presentations can closely mimic benign cystic lesions such as epidermal inclusion cysts or dermoid cysts, which are far more common in the eyelid region. This overlap in clinical and radiological features often leads to misdiagnosis and may result in unexpected intraoperative bleeding if the vascular nature of the lesion is not recognized preoperatively[3]. Recent available literature highlights the rarity of eyelid AVMs, with only isolated case reports and small case series. Mendonca et al[3] reported a preseptal AVM presenting as a non-specific eyelid mass without classical vascular signs, further underscoring the diagnostic challenges associated with these lesions. A recent case report by Ludovico et al[4] described an upper eyelid AVM associated with an orbital fistula, emphasizing the complexity of such lesions. Similarly advances in imaging and endovascular management have improved outcomes; however, accurate preoperative diagnosis remains difficult in cases with atypical presentations[5].

In this report, we describe an atypical case of an eyelid AVM presenting as a cystic mass that clinically and radiologically mimicked an epidermal inclusion cyst. The absence of classical vascular features and misleading imaging findings make this case particularly unique. This case aims to highlight the importance of considering vascular malformations in the differential diagnosis of atypical eyelid masses and reinforces the role of histopathological examination in establishing a definitive diagnosis.

CASE PRESENTATION

Chief complaints

An 18-year-old female presented with a swelling over the temporal aspect of the left upper eyelid for two years.

History of present illness

The swelling was insidious in onset, initially small, and gradually increased to its current size. There was no associated pain, discharge, redness, proptosis, or diminution of vision.

History of past illness

The patient had no past history of trauma or ocular surgery. She had no known comorbidities.

Personal and family history

The patient resided in a semi-urban area. Sleep, appetite, and bowel and bladder habits were normal. There was no family history of similar illness.

Physical examination

On examination, a well-defined, localized mass was noted in the temporal aspect of the left upper eyelid, measuring approximately 30 mm × 20 mm (Figure 1). The lesion was firm in consistency, non-tender, and non-pulsatile. The overlying skin appeared normal, with no erythema, ulceration, or visible dilated vessels. The mass was freely mobile over the underlying structures and not adherent to the skin. There was no associated warmth or bruit, and no increase in size on Valsalva maneuver. Transillumination test was negative. Best-corrected visual acuity was 6/6 in both eyes. Anterior and posterior segment examinations were within normal limits.

Figure 1 Preoperative clinical photograph showing left upper eyelid swelling. Frontal view of the patient demonstrating a well-defined swelling in the temporal aspect of the left upper eyelid, with normal overlying skin and no visible vascular changes such as discoloration or dilated vessels. The contralateral eye appears normal.

Laboratory examinations

Routine hematological investigations were within normal limits. The mass was excised in toto and sent for histopathology. Histopathological examination revealed multiple variably sized, irregular, tortuous, thin-walled vascular channels lined by a single layer of flattened endothelial cells. Few areas show interconnected congested veins and empty vessels (lymphatics). Areas of organized thrombus formation with focal calcification and fibroblastic proliferation of the vessel wall were noted. No evidence of malignancy was seen. These findings confirmed the diagnosis of a combined veno-lymphatic malformation (Figure 2).

Figure 2 Histopathological features of the lesion (hematoxylin and eosin staining). A: Low-power view showing interconnected congested veins (black arrow) and empty spaces i.e., lymphatics (shown by star) [hematoxylin and eosin (H&E), × 2] suggestive of a combined veno-lymphatic malformation; B: Higher magnification demonstrating irregular, tortuous vessels lined by a single layer of endothelial lining (black arrow) (H&E, × 10).

Imaging examinations

Computed tomography (CT) scan of the orbits and brain demonstrated a well-defined soft tissue lesion in the left periorbital and supraorbital frontal scalp region without underlying bony involvement, suggestive of an epidermal inclusion cyst (Figure 3).

Figure 3 Computed tomography of the orbits showing left upper eyelid lesion. Axial non-contrast computed tomography image demonstrating a well-defined soft tissue lesion in the left periorbital region (orange arrow) involving the upper eyelid and supraorbital area without evidence of underlying bony erosion or intraorbital extension. The imaging features were suggestive of a benign cystic lesion, such as an epidermal inclusion cyst.

FINAL DIAGNOSIS

Slow flow AVM (combined veno-lymphatic variety) of the left upper eyelid.

TREATMENT

Complete surgical excision of the lesion was performed under general anesthesia. A skin crease incision was marked over the upper eyelid. The lesion was carefully dissected in the subcutaneous plane, taking care to preserve surrounding structures. Bipolar cautery was used for meticulous hemostasis, and small feeding vessels encountered during dissection were coagulated. The mass was excised en bloc with minimal intraoperative blood loss (Figure 4).

Figure 4 Intraoperative photograph showing excision of the eyelid lesion. Intraoperative view of the left upper eyelid demonstrating a well-circumscribed vascular mass in the temporal region. The lesion is being carefully dissected from surrounding tissues, with visible vascularity and feeding channels. The specimen appears as a well-circumscribed, lobulated, reddish-brown soft tissue mass measuring approximately 2 cm in greatest dimension, consistent with a vascular lesion.

OUTCOME AND FOLLOW-UP

The postoperative period was uneventful. The surgical site healed well, and no recurrence was observed at one year follow-up. The patient achieved an excellent cosmetic outcome (Figure 5).

Figure 5 Postoperative clinical photograph showing resolution of the eyelid lesion. Frontal view of the patient demonstrating complete resolution of the swelling in the left upper eyelid following surgical excision, with well-healed surgical site and satisfactory cosmetic outcome at one year follow up. The contour of the eyelid appears normal with no evidence of recurrence.

DISCUSSION

Periocular AVMs are particularly uncommon and pose diagnostic and therapeutic challenges due to their variable presentation and potential for significant complications. Although present at birth, these lesions may remain clinically silent for years and manifest later due to hormonal changes, trauma, or progressive vascular remodelling[6]. According to the International Society for the Study of Vascular Anomalies classification, AVMs are categorized as fast flow vascular malformations, distinct from slow-flow lesions such as venous or lymphatic malformations[7]. Our patient had features of a slow flow AVM most likely a combined veno-lymphatic malformation as confirmed on histopathology.

The clinical presentation of eyelid AVMs is highly heterogeneous. Classical signs such as pulsatility, bruit, compressibility, and overlying skin changes may aid diagnosis; however, atypical presentations without these features are increasingly reported. In our case, although certain features such as the relatively larger size and gradual enlargement were atypical for a simple epidermal inclusion cyst, the absence of characteristic vascular findings lowered the preoperative suspicion of a vascular malformation. In such scenarios, AVMs may closely mimic common benign lesions such as epidermal inclusion cysts or dermoid cysts. Alsabbagh et al[8] have similarly highlighted that absence of vascular signs can lead to diagnostic confusion and unexpected intraoperative bleeding.

Imaging plays an important role in the evaluation of vascular lesions. CT scan is useful for assessing lesion extent and bony involvement, whereas magnetic resonance imaging (MRI) provides superior soft tissue characterization and helps identify flow-related features. However, as demonstrated in our case, imaging findings may be misleading in lesions lacking overt vascular characteristics, leading to an erroneous diagnosis of cystic lesions which was a limitation in our case. In such situations, ancillary investigations such as fine needle aspiration cytology, which may yield frank blood, can provide an important clue toward an underlying vascular etiology[9]. In addition, contrast-enhanced CT, MRI with assessment of flow voids, magnetic resonance angiography, CT angiography, and Doppler ultrasound may serve as practical first-line imaging tools for the evaluation of eyelid masses with suspected vascular origin.

The differential diagnosis of a superotemporal eyelid mass includes a broad spectrum of lesions. Common entities include epidermal inclusion cysts and dermoid cysts. However, vascular lesions such as capillary hemangioma, venous malformation, and lymphatic malformation must also be considered. Other important differentials include hemangiopericytoma and lacrimal gland lesions, particularly in superotemporal locations. Distinguishing these entities is critical, as vascular lesions require specific preoperative evaluation and surgical precautions.

Histopathological examination remains the gold standard for diagnosis. The characteristic features include variably sized, dilated vascular channels lined by flattened endothelial cells, often associated with thrombus formation, calcification, and fibroblastic proliferation. These findings help distinguish AVMs from other vascular or cystic lesions and were consistent with those observed in our case[10-12].

Management of AVMs depends on lesion size, location, and hemodynamic behaviour. Treatment options include surgical excision, endovascular embolization, sclerotherapy, or a combination of these modalities. Recent studies suggest that a multidisciplinary approach may improve outcomes, particularly in complex or high-flow lesions[13]. However, for small, localized eyelid AVMs, complete surgical excision alone can be curative, as demonstrated in our case. Careful surgical planning is essential to minimize intraoperative bleeding and avoid damage to surrounding structures. AVMs are associated with a risk of recurrence if the nidus is incompletely excised. Therefore, long-term follow-up beyond one year is recommended, even in cases with complete clinical resolution[14].

The uniqueness of our case lies in its atypical presentation as a cystic eyelid mass, both clinically and radiologically mimicking an epidermal inclusion cyst or dermoid cyst. Unlike most reported cases, there were no classical vascular features, and imaging further reinforced a misleading diagnosis. Such presentations are atypical and highlight the importance of maintaining a high index of suspicion for vascular anomalies even in apparently benign eyelid lesions.

CONCLUSION

Eyelid AVMs can masquerade as benign cystic lesions, posing a significant diagnostic challenge. Any eyelid mass > 2 cm with history of gradual enlargement and atypical location should be evaluated thoroughly to rule out vascular etiology before planning surgical excision to avoid misdiagnosis and intraoperative complications.