Neurothekeomas : Multiple Symmetric Tumors in Both Hands
Neurothekeoma is a rare benign tumor, which is suspected to arise from peripheral nerve sheath cells. Neurothekeomas are often solitary, reddish-brown, painless, and firm cutaneous nodules. The tumor occurs most frequently in the craniofacial region and upper extremities. Despite being benign, neurothekeomas may penetrate muscles, subcutaneous tissues, and vasculature. In this study, multiple areas of adjacent periosteal reaction were found. Histologically, neurothekeomas are classified into myxoid, cellular, or mixed type.

A 61-year-old man had tumors that gradually increased in size in both hands for 7 years. Initially, these masses were pea sized and were located at the palmar side of the index, middle, and ring fingers. Subsequently, multiple masses in the size range of 2.0 cm × 2.0 cm to 3.0 cm × 4.0 cm were observed, accompanied with flexion restriction of the metacarpophalangeal joint. Plain radiographs (Figure 1) revealed multiple soft tissue–density masses in the hand and wrist. Adjacent bones showed solid periosteal reactions in multiple proximal phalanges and the thumb metacarpal. Dystrophic calcification was found at the palmar side of the right middle finger. The patient underwent surgical resection, and surgical findings revealed that the masses were wrapped around adjacent vessels and nerves. Histological examination indicated neurothekeomas (Figure 2), with the following immunohistochemistry results: S-100 (positive) and glial fibrillary acidic protein (negative). No specific genetic syndrome was identified; the patient was not tested for neurofibromatosis-1.

In summary, this patient had tumors of the myxoid type, with myxoid matrix accounting for more than 50% of the tumors. The different histological subtypes are classified based on their cellularity, mucin content, and growth pattern. Furthermore, the myxoid subtype usually shows immunohistochemistry staining positive for peripheral neural antigens (S-100). The differential diagnosis of neurothekeomas includes giant cell tumor of tendon sheath, hemangioma, lipoma, and Maffucci syndrome. Giant cell tumor of tendon sheath occurs mostly at the palmar side of the fingers or palms, attached to the tendon, which can be hypointense on T2-weighted images. Ultrasonography is helpful in the diagnosis of hemangioma because of the superior detection of increased intralesional vascularity.

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