Indian Journal of Dermatology
: 2021  |  Volume : 66  |  Issue : 4  |  Page : 416--419

A Case of Dermal Nerve Sheath Myxoma: A Different Tumor from Cellular Neurothekeoma

Huimin Meng, Cunhuo Jiang 
 Department of Dermatology, The Second People's Hospital of Chengdu, Chengdu 610000, Sichuan, China

Correspondence Address:
Huimin Meng
Department of Dermatology, The Second People's Hospital of Chengdu, Chengdu 610000, Sichuan

How to cite this article:
Meng H, Jiang C. A Case of Dermal Nerve Sheath Myxoma: A Different Tumor from Cellular Neurothekeoma.Indian J Dermatol 2021;66:416-419

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Meng H, Jiang C. A Case of Dermal Nerve Sheath Myxoma: A Different Tumor from Cellular Neurothekeoma. Indian J Dermatol [serial online] 2021 [cited 2023 Feb 7 ];66:416-419
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A 28-year-old Chinese female presented with a 10-year history of a nodule on her left palm [Figure 1], which was slow-growing. In the previous 3 months, the nodule had presented with tenderness. She denied drainage or bleeding. No previous history of trauma, insect bites, or scarring to the area was elicited.{Figure 1}

Physical examination revealed a 1 cm nodule of skin color on the left palm with tenderness, which was firm, nonmobile, and irregular margin.

Complete excision and microscopic examination were performed, showing multiple well-defined various sized lobules separated by fibrous septa in the dermis [Figure 2]. The lobules consisted of large amounts of myxoid matrix and a few scattered spindled stellate cells [Figure 3]. No atypical cells or mitotic figures were seen. Immunohistochemical analyses were positive for S100 protein and vimentin. Ki-67 labeling index was <5%, but negative for glial fibrillary acidic protein (GFAP), CD 34, CD10, Carcinoembryonic antigen (CEA), and Pan cytokeratin (PCK) [Figure 4]. A diagnosis of a dermal nerve sheath myxoma (DNSM) was established [Figure 5],[Figure 6],[Figure 7]. The patient was reviewed 11 months later with no evidence of recurrence.{Figure 2}{Figure 3}{Figure 4}{Figure 5}{Figure 6}{Figure 7}

The first nerve sheath myxoma was reported in the literature by Harkin and Reed in 1969, which originated from the peripheral nerve sheath.[1] And the term neurothekeoma (NT) was introduced in 1980 by Gallager and Helwig.[2] With the increasing number of recent immunohistochemical and ultrastructural reports, the data indicate that NSM exhibits true nerve sheath differentiation, whereas no such compelling evidence exists for cell neurothekeomas (CNT). More evidence shows that NSM is different from CNT by histogenesis, morphology, and immunophenotype.

NSM present with solitary, superficial, multinodular masses in the 0.5–2.5 cm size range, a peak incidence in the third and fourth decades of life,[3],[4] and an anatomic distribution that most of them (86%) occurred in the extremities,[4] no gender difference. CNT also occur as pink erythematous, dome-shaped, solitary, asymptomatic papule, mostly during the second and third decades of life, demonstrating a female predominance (1:1.8).[5] The tumors mostly arise on the upper extremities and head and neck.[5] The mean tumor size is 1 cm, and 90% are smaller than 2 cm.[5],[6]

NSM present as well-circumscribed, non-encapsulated, lobulated lesions, exhibiting proliferation of spindle, stellate, and occasionally epithelioid-shaped cells in an abundant myxoid stroma.[4] Meanwhile, no mitosis or necrosis was evident in the lobular.[4] CNT topically had spindled and epithelioid mononuclear neoplastic cells with relatively abundant cytoplasm;[6] most cases were poorly marginated.[5] The majority of CNT also had occasional multinucleated tumor cells. The tumor cells had a strong tendency for whorled growth, and oftentimes, focal fascicular growth was also present. Nuclear atypia and mitosis were common.[5],[6]

NSM was immunoreactive for S100 protein (100%[3]), often positive for GFAP and CD57,[3],[4] and negative for A melanoma monoclonal antibody (NKI)/C3. CNT was positive for NKI/C3 (100%), Neuro-specific enolase (NSE) (89%), CD10, Mit-F, CD68, α-(Smooth muscle actin) SMA, but negative for S100 protein, GFAP, Melan-A, and CD34.[5],[6],[7]

Other histological differential diagnoses of nerve sheath myxoma include myxoid neurofibroma (MN), perineurioma, and superficial acral fibromyxoma. MN typically has collagen bundles within the myxoid stroma, is not mitotic, and lacks a lobular structure.[8] The tumors consisted of interlacing bundles of Schwann cells, which of the nucleus' apex is slightly curved, comma-like, or wavy. They show patchy S100 (Schwann cells) and CD34 (fibroblast) expression simultaneously.[9] Perineuriomas show a whorled fascicular pattern in a myxoid or collagenous stroma. They can be differentiated from NSM on immunohistochemistry as perineuriomas show strong positivity for EMA and are negative for S100, GFAP, and CD34.[10] Superficial acral fibromyxoma is composed of stellate and spindle-shaped fibroblast-like tumor cells with storiform and fascicular or random growth patterns in a variable degree of admixed myxoid or collagenous matrix with lobular pushing or infiltrative margin in the dermis. There is also blood vessel proliferation, and mast cells are present throughout the dermis with mild nuclear atypia. Tumor cells show positivity for CD34, CD99, vimentin, but EMA results are inconsistent.[11]

Surgical excision was the most common treatment for NSM. NSM has a relatively high local recurrence rate (57%)[4] than the local recurrence rate (7.3–7.5%) in CNT.[5],[6]

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