Dermal nerve sheath myxoma is a rare benign peripheral nerve sheath tumor that exhibits Schwann cell differentiation.
Histologically, dermal nerve sheath myxoma shows a characteristic lobulated growth pattern with sharply demarcated lobules separated by fibrous tissue (Figure 11, A).
The differential diagnosis of dermal nerve sheath myxoma includes acral fibromyxoma, superficial angiomyxoma, soft tissue myoepithelioma, and cellular neurothekeoma.
The differential diagnosis of cellular neurothekeoma includes FH, dermal nerve sheath myxoma, and plexiform fibrohistiocytic tumor.
Nerve sheath myxoma: a clinicopathologic and immunohistochemical analysis of 57 morphologically distinctive, S100 protein- and GFAP-positive, myxoid peripheral nerve sheath tumors with a predilection for the extremities and a high local recurrence rate.
Dermal nerve sheath myxoma. A, The tumor shows a multilobulated growth pattern separated by fibrous septa.
Architectural Patterns of Cutaneous Spindle Cell Neoplasms Fascicular pattern Intradermal nodular fasciitis Acral fibromyxoma Pilar leiomyoma Leiomyosarcoma Kaposi sarcoma Angiosarcoma Atypical fibroxanthoma Storiform/whorled pattern Fibrous histiocytoma (dermatofibroma) Soft tissue perineurioma Dermatofibrosarcoma protuberans Lobulated/plexiform pattern Dermal nerve sheath myxoma Cellular neurothekeoma Plexiform schwannoma Biphasic pattern Myofibroma/myopericytoma Nonmesenchymal neoplasms mimicking cutaneous spindle cell mesenchymal tumors Spindle cell squamous cell carcinoma Desmoplastic melanoma Table 2.
Moreover, the neoplasm exhibited an abundant mucinous background, resembling
nerve sheath myxoma, a benign entity described in people, but with no animal counterpart.
Various other terms also had been used for the dermal neoplasms, such as neurothekeoma,
nerve sheath myxoma, benign myxoid tumor of nerve sheath, perineural myxoma, bizarre cutaneous neurofibroma.1,3 However, some authors consider that the term pacinian perineural cell fibroma may describe it better.2
Other pathological differential diagnoses of our case would include hybrid peripheral nerve sheath tumors, perineurioma, cellular neurothekeoma,
nerve sheath myxoma (classic neurothekeoma), desmoplastic neurothekeoma, superficial angiomyxoma (cutaneous myxoma), (16) solitary neurofibroma with prominent differentiation of Meissner bodies, or spindle cell carcinoma.
The histologic differential diagnosis in this case included a
nerve sheath myxoma and a neurofibroma with myxomatous change, in addition to the myxoid angiomyoma.
(16)
Nerve sheath myxomas and myxoid neurofibroma contain dense, wavy collagen structures; prominent, spindly nuclei; and occasional lymphocytes.