Pleomorphic mastocytoma associated with loss of chromosome 5, PDGFRA, and HRAS mutations: A case of cutaneous mastocytosis with severe atypia and indolent behavior

Abstract

A 21-year-old female presented with a 5-year history of an erythematous papule on her right breast. The biopsy showed a dense, dermal nodular infiltrate, extending focally into the subcutaneous tissue. The infiltrate was composed predominantly of pleomorphic cells with bi-lobed, multi-lobed, horseshoe, or ring-shaped nuclei. There was a smaller subset of monomorphous cells characterized by a round, reniform, or elongated single-lobed nucleus. Accompanying cells included few foamy histiocytes, lymphocytes, and numerous scattered eosinophils. No necrosis, vascular invasion, or ulceration was present. The pleomorphic and monomorphic granular cells were positive for Giemsa stain as well as for tryptase, CD117, CD68, CD2, and CD30 immunohistochemistry and negative for S100, CD1a, myeloperoxidase, lysozyme, and CD56. Clinical examination was negative for any additional similar lesions and serum tryptase was within normal limits. The bone marrow was not biopsied. In addition, fluorescent in situ hybridization revealed multiple clones with loss of number 5 chromosome and PDGFRA and HRAS mutations. The lesion did not recur or progress after a 6-year clinical follow-up. To our full knowledge, we report the first case of pleomorphic mastocytoma with loss of chromosome 5 and PDGFRA and HRAS mutations.

Case report of a clinically indolent but morphologically high‐grade cutaneous mast cell tumor in an adult: Atypical cutaneous mastocytoma or mast cell sarcoma?

“…Recently, a case of a pleomorphic mastocytoma was presented with distinctive genetic aberrations. 33 However, in contrast to our case, mitotic figures were not present and recurrence of the lesion was not mentioned. On the basis of the above‐mentioned features, we argue that the lesion should be diagnosed as an atypical mastocytoma of the skin, borderline to a sarcoma.…”

“…28,[34][35][36][37] All MCS cases showed extensive local destructive growth, "metastases" and/or secondary systemic involvement, mostly in form of an MCL. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] F I G U R E 2 Skin excision in 2014. A, Overview of the lesion of diffuse sheets of epithelioid cells in the dermis (H&E, magnification Â10).…”

“… 23 There are 13 cases of MCS or MCS‐like neoplasms in adults reported in the English literature, including cutaneous and extracutaneous forms. 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 Additionally, there are five reported cases of systemic mastocytosis with sarcomatous growth of mast cells, all in adults and extracutaneous. 28 , 34 , 35 , 36 , 37 All MCS cases showed extensive local destructive growth, “metastases” and/or secondary systemic involvement, mostly in form of an MCL.…”

“… 28 , 34 , 35 , 36 , 37 All MCS cases showed extensive local destructive growth, “metastases” and/or secondary systemic involvement, mostly in form of an MCL. 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 …”

Pathomorphology of cutaneous mastocytosis

“…Могут встречаться участки со значительным содержанием эозинофилов в инфильтрате. Клетки представлены выраженным ядерным полиморфизмом с двудольными и многодольными ядрами [20,21]. Тучные клетки овальной и кубоидальной форм, значительная часть их дегранулирована, контуры размыты, цитоплазма слабоокрашена.…”