Mast cell sarcoma: clinicopathologic and molecular analysis of 10 new cases and review of literature

Mast cell sarcoma: 2 Mayo Clinic cases

“…The observations from the current study and those of Matsumoto, et al 3 confirm differences in neoplastic mast cell staining pattern and KIT mutation expression between MCS (often KIT unmutated and variable expression of CD25) and SM (often expressing both KIT mutation and CD25). Treatment outcome in MCS, often consisting of surgical resection and involved-field radiation, was poor and might warrant addition of chemotherapy, perhaps in the form of cladribine, 4 midostaurin, 5 or avapritinib.…”

“…In the particular study, 3 cell morphology was described as being pleomorphic with large tumor cells expressing CD43, CD117, CD33, CD13, and mast cell tryptase, in all evaluated cases, while expression of CD25, CD2, CD30, and CD68 was variable; of note, none of the patients evaluated expressed KIT D816V, although two were reported to harbor other KIT mutations. The report from Matsumoto et al 3 included two Mayo Clinic cases that are highlighted in the current report, which also provides additional diagnostic and treatment details and follow‐up information.…”

“…1 MCS should be distinguished from systemic mastocytosis (SM). 2 A recent communication by Matsumoto, et al 3 cited a total of 34 reported cases of MCS and described 10 new cases (median age 54 years), equally affecting men and women, with bone involvement in 90% of the cases; concurrent SM was documented in only one case, whereas mast cell mediator symptoms were reported in 3 patients and elevated serum tryptase in 6; two patients had prior history of germ cell tumors. 3 In the particular study, 3 cell morphology was described as being pleomorphic with large tumor cells expressing CD43, CD117, CD33, CD13, and mast cell tryptase, in all evaluated cases, while expression of CD25, CD2, CD30, and CD68 was variable; of note, none of the patients evaluated expressed KITD816V, although two were reported to harbor other KIT mutations.…”

Standards of Pathology in the Diagnosis of Systemic Mastocytosis: Recommendations of the EU-US Cooperative Group

“…3,20,24 The rare forms of localized MC neoplasms encompass MC sarcoma (MCS) and the reintroduced benign extracutaneous mastocytoma (ECM). 25,26 WHO-approved variants of SM are shown in Table II.…”

The international consensus classification of eosinophilic disorders and systemic mastocytosis

“…MCS is a localized, destructive MC infiltration with an aggressive behavior, and around 20% of MCS are associated with underlying SM. 107 If the MCS develops in a patient with SM, it is more appropriate to call those cases MCS-like progression of the SM rather than MCS. It is known that MCS associated with SM usually carries a KIT D816V mutation, whereas most cases of primary MCS lack the KIT D816V mutation.…”