Surgical management of adult hand macrodactyly in a 49-year-old patient: A case report

Abstract

BACKGROUND

Macrodactyly is a rare congenital malformation characterized by an increase in the size of all structures of a digit, accounting for less than 1% of all congenital upper extremity conditions.

CASE SUMMARY

We report a case involving a 49-year-old woman who presented for the first time with untreated, radial-sided hand macrodactyly. We performed soft tissue debulking, amputation, median nerve neurotomy and coaptation, and carpal tunnel release. At the 6-year follow-up, no significant growth was observed in the bone or soft tissue of the affected area.

CONCLUSION

Tissue overgrowth in patients with progressive macrodactyly can continue and progress excessively with age. Median nerve neurotomy and coaptation play a crucial role in preventing recurrence of the deformity.

Key Words: Macrodactyly; Surgery; Management; Hand; Case report

Core Tip: Macrodactyly is a rare congenital malformation, constituting less than 1% of congenital upper extremity anomalies. It typically involves enlarged structures of a digit, often managed through various surgical methods including tissue reduction and nerve adjustments. As first suggested by Tsuge, hypertrophic nerves are thought to drive the overgrowth. The condition is often associated with adipose lesions categorized as intraneural or extraneural lipomas and lipomatosis of the nerve, frequently affecting the median nerve. Managing and preventing recurrence remains a clinical challenge, especially in adults.

INTRODUCTION

Macrodactyly is a rare congenital malformation characterized by an increase in the size of all structures of a digit, accounting for less than 1% of all congenital upper extremity conditions[1-3]. Surgical approaches to macrodactyly include soft tissue and skeletal reduction, epiphysiodesis for adult-sized digits, partial amputation, ray amputation, and digit or toe free tissue transfer. Tsuge[4] popularized the theory that the hypertrophic nerve drives digital overgrowth in macrodactyly. Adipose lesions of the nerve have historically been classified as intraneural and extraneural lipomas, and lipomatosis of the nerve (LN), characterized by the presence of abundant fibroadipose tissue within the epineurium[5]. Clinical studies describe LN as a focal distal abnormality of peripheral nerves, with the median nerve at the wrist most commonly affected[6].

Macrodactyly of the hand represents a significant surgical challenge, particularly in adults. The primary concern in treating this condition is the prevention of recurrence. The patient was informed that information regarding her case would be submitted for publication, and she provided her consent.

CASE PRESENTATION

Chief complaints

A 49-year-old female who had macrodactyly of the right thumb since birth presented to address abnormal enlargement of the thumb and index finger becoming progressively more noticeable over the last decade.

History of present illness

At birth, the patient showed macrodactyly of the right thumb. Ten years prior to presentation at our clinic, she had begun to observe progressive, disproportionate growth of the thumb and index finger. More recent to the clinic presentation, she had begun to experience numbness, tingling, and pain localized to the tip of the thumb.

History of past illness

The patient had no significant medical history, had not undergone any surgeries, and reported having no chronic diseases. She reported being a non-smoker and drinking alcohol socially.

Personal and family history

The patient reported no family history of malignant tumors or similar conditions.

Physical examination

The overgrowth was predominantly limited to the thenar compartment and digital nerve distribution of the thumb. The right thumb showed hypertrophy, hyperplasia of fat tissue around the phalanges and the first metacarpal bone, and skin hypoesthesia. Movement of the right carpal metacarpal joint was limited. The metacarpophalangeal (MCP) and interphalangeal (IP) joints of the right thumb and the distal interphalangeal (DIP) joint of the index finger were nonfunctional, but the MCP and the proximal interphalangeal (PIP) joints of the index finger were normal. Wrist function was normal.

Laboratory examinations

No abnormalities were found in the laboratory examinations.

Histopathological examination

A micrograph (Toluidine Blue stain) of a biopsy from the median nerve revealed an enlarged peripheral nerve. Fatty infiltration within the peripheral nerve and an abundance of adipose tissue surrounding the median epineurium were also noted (Figure 1).

Figure 1 Histopathology finding. Micrograph of a median nerve biopsy (Toluidine Blue stain) showing an enlarged peripheral nerve, fatty infiltration within the peripheral nerve, and an abundance of fat around the median epineurium (magnification × 40).

Imaging examinations

X-ray imaging revealed enlargement of the phalanges and of the first metacarpal bone of the right thumb, with the distal phalanges exhibiting "mushroom-like" changes. Notable juxta-articular new bone formation was observed at the carpometacarpal, MCP, and IP joints of the thumb, accompanied by disappearance of joint space. Osteophytes had also developed at the MCP and PIP joints of the index finger, where the DIP joint space had vanished (Figure 2). Furthermore, the space between the proximal parts of the first and second metacarpal bones, as well as the scaphoid, trapezium, and trapezoid bones, had diminished. New bone formation was also noted in the distal and proximal regions of the radius. CT scans and three-dimensional reconstructions further demonstrated the extent of degeneration in the hand joints and the tortuosity of the median nerve (Figure 3).

Figure 2 X-ray views of the patient's hand and forearm. A and B: Representative preoperative radiographs showing substantial osteophyte formation around the thumb and index finger joints, with the space between the proximal parts of the first and second metacarpals, as well as the scaphoid, trapezium, and trapezoid bones, having disappeared; C and D: Representative anteroposterior and lateral radiographs of the elbow, revealing hyperostosis at the proximal radius where muscle attachments are present (arrows).

Figure 3 Computed tomography and 3D reconstruction imaging of the affected limb. A: Overgrowth of the bones; B: Thickening and tortuosity of the median nerve (arrow) at the wrist level.

Ultrasound examination revealed tissue hypertrophy and nerve involvement, with a hypertrophic distribution of adipose tissue noted subcutaneously, intermuscularly, and intramuscularly. The median nerve appeared enlarged and exhibited an uneven echogenicity, with a slight deviation noted in the middle of the right forearm. A longitudinal ultrasound image at the level of the proximal carpal tunnel displayed a co-axial cable-like appearance (Figure 4).

Figure 4 Longitudinal ultrasound image at the level of the proximal carpal tunnel. Hypoechogenicity and enlargement of the median nerve is shown.

FINAL DIAGNOSIS

Macrodactyly of the hand.

TREATMENT

Surgery was performed under general anesthesia with a tourniquet. A racket-shaped incision was made from the MCP joints of the thumb to the proximal forearm. Osteotomy and debulking of the entire tissue at the proximal first metacarpals were performed, preserving the surrounding nerves and blood vessels. Osteophytes around the MCP joint of the index finger were removed, and DIP joint arthrodesis was performed. After releasing the carpal tunnel, a 0.5 cm segment of the median nerve was excised from the horizontal wrist stria, and end-to-end coaptation was performed. After the tourniquet was loosened, hemostasis was achieved with electrocautery, excess skin and soft tissue were removed, and the incision was closed. Postoperatively, the patient received antibiotics and analgesics, underwent periodic wound care, and performed exercises for the MCP joint of the index finger.

Intraoperative findings

A significant accumulation of subcutaneous adipose tissue was noted along the median nerve of the right upper limb. The median nerve, along with the nerves of the thumb and index finger, appeared markedly thickened. Bone hyperplasia was observed around the MCP joint of the index finger, and some of the muscles innervated by the lesion exhibited adipose infiltration. Upon transection of the median nerve, it was discovered that an extensive amount of fatty tissue was interspersed among the bundles of the nerve fibers (Figure 5).

Figure 5 Preoperative and intraoperative appearance of the patient. A and B: Anteroposterior (A) and lateral (B) views of the hands affected by macrodactyly; C: Thickened median nerve (indicated by a black arrow); D: Extensive fatty tissue infiltration among the nerve fiber bundles.

OUTCOME AND FOLLOW-UP

At the 6-wk postoperative visit, the surgical wound was in good condition, and motor function of the MCP joint of the index finger had improved, though sensory deficits persisted according to the distribution of the median nerve (Figure 6). Six years later, the patient reported normal sensation in the thenar area of the right palm but continued to experience numbness at the fingertips of the index and middle fingers. The range of flexion and extension of the MCP joint of the index finger was 20-70°; the IP and DIP joints could not move, though the function of the middle finger was normal (Figure 7). Tinel's sign persisted at the coaptation site of the median nerve. These results indicate that while median nerve neurotomy and coaptation play a crucial role in preventing the recurrence of deformity, long-term sensory numbness may persist.

Figure 6 Postoperative external and internal views of the affected limb. A and B: Representative images showing the surgical wound in good condition, with no signs of infection at the operation site; C and D: Representative X-ray images showing post-amputation of the thumb and osteophyte removal surgery of the index finger.

Figure 7 Six-year postoperative external and internal views of the hand. A and B: Post-debulking surgery images showing no significant overgrowth of soft tissue in the surgical area; C: X-ray image showing no significant increase in osteophytes around the first carpometacarpal joint, interphalangeal joint, and metacarpophalangeal joint of the index finger.

DISCUSSION

The patterns of overgrowth include isolated overgrowth (nerve-territory oriented and lipomatous macrodactyly) and syndromic overgrowth (CLOVES syndrome, Klippel-Trenaunay syndrome, Proteus syndrome, Parkes Weber syndrome, neurofibromatosis type I)[7]. LN is a rare, tumor-like condition that affects peripheral nerves, particularly the median nerve[8]. In approximately 62% of LN cases, overgrowth is observed and consistently occurs distal to the affected nerve[9].

The reason for bony changes could be a misalignment of articular surfaces, leading to severe secondary degenerative joint changes and new bone formation[10]. Nerve-territory overgrowth typically ceases or slows down at puberty. However, in this case, with increasing age, the affected phalangeal bone enlarged and thickened, and the space between the IP joint, MP joint, and radial carpal bone gradually diminished, accompanied by the formation of numerous osteophytes, resulting in dysfunction of the phalangeal joints. At the 6-year follow-up, it was found that the bone in the lesion area did not continue to grow significantly, suggesting that median nerve neurotomy and coaptation play an important role in preventing the recurrence of deformity. Anteroposterior and lateral radiographs of the elbow showed new bone formation at some muscle attachments at the proximal radius, which were innervated by the median nerve. Wehrli et al[11] demonstrated that in the upper extremity, LN can involve the entire peripheral nerve, up to the roots of the brachial plexus. We concluded that the lesion along the median nerve might be more extensive in this case, but further examination was not conducted to confirm this. The role of nerves as a conductor within bone is crucial, sometimes accelerating osteogenesis and at other times impeding the process to maintain bone metabolism in harmony[12]. However, the specific mechanism linking the median nerve and abnormal skeletal growth in macrodactyly remains elusive.

LN appears as "lotus root-like" on the axial ultrasound plane and "cable-like" on the longitudinal plane, with hypoechoic fascicles interspersed with hyperechoic adipose tissue, which corresponds to MRI findings[13]. In our case, the longitudinal ultrasound at the level of the proximal carpal tunnel demonstrated a cable-like appearance, significantly thicker than on the left side. These findings, consistent with LN, were supported by histopathological imaging, which revealed a large accumulation of adipose tissue around the nerve fiber bundles. Additionally, a median nerve biopsy showed an enlarged peripheral nerve with fatty infiltration among the nerve fascicles. Based on the clinical presentation, ultrasonography, and pathological findings, we concluded this to be a case of LN.

In the reported case, we performed soft tissue debulking, amputation, median nerve neurotomy and coaptation, and carpal tunnel release. Gluck et al[14] have emphasized that complete nerve excision is necessary due to the nerve-driven overgrowth of the digit, which is thought to be mediated by diffusible growth factors. The postoperative follow-up indicated that median nerve neurotomy and coaptation were essential to prevent the recurrence of deformity; however, complications such as sensory numbness in the innervated area may persist long-term. To mitigate these complications, we recommend a comprehensive postoperative rehabilitation plan that includes physical therapy and sensory training. Additionally, regular follow-up visits are essential to promptly identify and address potential issues. Some researchers believe that amputation should be performed to prevent further complications when the affected limb cannot be maintained or the fingers cannot function properly after therapy[15,16].

CONCLUSION

Tissue overgrowth in patients with progressive macrodactyly can continue and progress excessively with age. Median nerve neurotomy and coaptation play a crucial role in preventing the recurrence of deformity, although they may lead to long-term complications.