Soft tissue high grade myoepithelial carcinoma with round cell morphology: report of a newly described entity with EWSR1 gene rearrangement

The case of soft tissue malignant myoepithelioma is presented including clinicopathological, immunohistochemical and cytogenetic findings. A 36-year-old Saudi male patient suffered from large mass involving right scapula and right shoulder joint measuring 14x13x11 mm. Core biopsy revealed sheets and lobules of poorly differentiated small malignant cells with marked atypia and frequent mitosis. Initially, immunohistochemistry was reactive for vimentin, pan-cytokeratin, EMA and CD99. The case was negative for desmin, SMA, CD34, S-100 protein and GFAP. FISH analysis exhibited negativity for SS18 (18q11.2) gene rearrangement and positivity for EWSR1 (22q12) gene rearrangement and a diagnosis of Ewing/PNET was considered. Clinical behavior and therapeutic response did not match the diagnosis with re-evaluation. Wedge biopsy demonstrated aggregates of epithelioid cells besides calponin and P63 positivity. Final diagnosis of malignant myoepithelioma with EWSR1 gene rearrangement was issued; a new entity with aggressive course. Myoepithelial carcinoma of soft tissue exhibits a wide spectrum of cytomorphology with overlapping phenotype similar to other soft tissue sarcoma like synovial sarcoma, mesenchymal chondrosarcoma, epithelioid sarcoma as well as Ewing/PNET. Moreover, a new finding of EWSR1 gene rearrangement is recognized in malignant myoepithelioma with different fusion partners. Hence, myoepithelial carcinoma should be kept in mind in diagnosis of soft tissue tumors even with unusual phenotype and gene rearrangement.

Nonmutilating palmoplantar and periorificial kertoderma: a variant of Olmsted syndrome or a distinct entity?

BACKGROUND

Olmsted syndrome is a rare keratinization disorder characterized by mutilating palmoplantar and periorificial keratoderma as the two major diagnostic features. Some authors believe that atypical cases without this standard combination may not really belong to Olmsted syndrome. Herein, we describe two familial cases with congenital nonmutilating palmoplantar and periorificial keratoderma, and discuss their similarities and differences with Olmsted syndrome.

PATIENTS

The study included two sisters who presented with focal and punctate nonmutilating palmoplantar keratoderma (PPK), periorificial hyperkeratotic plaques, and widely distributed keratotic lesions. Fragile denuded areas of the skin were found in sites exposed to trauma. Fingernails showed a characteristic form of leukonychia.

RESULTS

Histopathology of plantar keratoderma showed psoriasiform hyperplasia with marked compact hyperkeratosis, while vicinity of denuded skin revealed thin parakeratotic zone and dissolution of the granular cell layer. Immunohistochemistry demonstrated suprabasal staining pattern for acidic keratin (AE1) and uniform positivity, starting four to six layers above the basal layer, for cytokeratin 10. Electron microscopy showed defective keratinization. Cytogenetic studies revealed normal karyotype and no chromosomal breakage.

CONCLUSION

Our cases share Olmsted syndrome in the early onset, and the presence of symmetrical PPK, periorificial keratoderma and keratotic lesions. However, the striking nonmutilating nature of PPK and the presence of unique features in our patients suggest a newly described keratinization disorder.