Plexiform Melanocytic Schwannoma: Report of a Second Case and Overview of a Rare Entity.

Autor:	Ranson M; Department of Pathology and Laboratory Medicine, Queen Elizabeth II Health Sciences Centre, Nova Scotia Health (Central Zone), Halifax, Nova Scotia, Canada., Lai J; Department of Anatomical Pathology (Dermatopathology), LifeLabs, Toronto, Ontario, Canada., Van Brenk B; Department of Surgery, Division of Plastic Surgery, Peterborough Regional Health Centre, Peterborough, Ontario, Canada., McCalmont TH; Departments of Pathology and Dermatology, University of California, San Francisco, CA, USA., Walsh NM; Department of Pathology and Laboratory Medicine, Queen Elizabeth II Health Sciences Centre, Nova Scotia Health (Central Zone), Halifax, Nova Scotia, Canada.; Department of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada; and.; Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
Jazyk:	angličtina
Zdroj:	The American Journal of dermatopathology [Am J Dermatopathol] 2022 Dec 01; Vol. 44 (12), pp. 943-947. Date of Electronic Publication: 2022 Nov 02.
DOI:	10.1097/DAD.0000000000002311
Abstrakt:	Abstract: The seminal case report of plexiform melanocytic schwannoma, published a decade ago, indicated that this is a rare variant of schwannoma demonstrating immunohistochemical expression of melanocytic markers, electron microscopic evidence of melanosome formation, and genetic features of a benign schwannoma. We report herein, a second example of this entity. Of added interest, our case showed pseudoglandular features, as previously recorded in other variants of schwannoma. A 66-year-old man presented with a cutaneous papule on the abdomen. Histopathologically, a vertically oriented, exoendophytic, folliculocentric, dermal tumor with a plexiform architecture was observed. This was composed of nodules and diverging fascicles of bland spindle-shaped cells. Notable interstitial mucin deposition conveyed a pseudoglandular appearance to the lesion. The spindled cells co-expressed S100, SOX10, and HMB45. A minority of cells expressed Melan-A and MiTF. EMA and claudin-1 stained capsular and perifascicular perineurial cells. Melanin was absent. Plexiform melanocytic schwannoma represents one of several nerve sheath tumors that peculiarly display evidence of melanocytic differentiation. These include melanocytoneuroma, pigmented neurofibroma (or melanocytic neurofibroma), and malignant melanotic schwannian tumor. Of importance, these proliferations can be mistaken for melanocytic tumors, including melanoma. In expanding the literature on this topic, we discuss steps required to distinguish plexiform melanocytic schwannoma from melanoma and other nerve sheath tumors with melanocytic differentiation. The possible pathogenesis of these unusual neoplasms is also addressed. Competing Interests: The authors declare no conflicts of interest. (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)
Databáze:	MEDLINE
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