Inflammatory leiomyosarcoma shows frequent co-expression of smooth and skeletal muscle markers supporting a primitive myogenic phenotype: a report of 9 cases with a proposal for reclassification as low-grade inflammatory myogenic tumor

AbstractInflammatory leiomyosarcoma (ILMS) is a very rare soft tissue tumor that usually follows an indolent clinical course, but long-term follow-up studies are lacking. Recent publications primarily focused on its genetic profile characterized by a near haploid genome. One study also showed these tumors to have upregulation of genes known to be crucial for skeletal muscle differentiation. Nevertheless, immunohistochemical expression of skeletal muscle markers, as well as markers that would help to distinguish ILMS from a long list of relevant differential diagnostic entities, has not been extensively studied. Nine cases of ILMS were collected and stained by a broad IHC panel which, besides others, contained MyoD1, myogenin, and PAX-7. A subset of cases was also analyzed by 2 different NGS assays and byMDM2 fluorescence in situ hybridization. Five male and 4 female patients ranged in age from 25 to 54  years (mean, 36 years). The tumors showed a predilection for intramuscular sites of the lower limbs (n = 4) and back (n = 2), whereas the remaining 3 cases affected an unspecified skeletal muscle, lung, and omentum. Follow-up with an average length of 10.6 years (range 0.5–22) was available for 8 patients. The omental tumor spread locally within the abdominal cavity, but the patient has been free of disease 7  years after treatment. None of the 5 patients with somatic soft tissue tumors (and follow-up longer than 1.5 years) had either recurrence or metastasis. Imm...
Source: Virchows Archiv - Category: Pathology Source Type: research