Thangaiah, Judith J.

Abstract: Kimura disease typically presents with painless head and neck swelling in young adults of Asian descent, accompanied by peripheral eosinophilia and elevated serum IgE. We report a case of Kimura disease in a woman in her early 30s presenting with a slowly enlarging epitrochlear mass, diffuse encasement of the median and medial brachial cutaneous nerves, and a concurrent prurigo nodularis-like papular rash affecting all 4 extremities. The diagnosis required over 1 year of investigation and 5 tissue specimens, including 2 nondiagnostic core-needle biopsies, before near total excision was performed. The excision revealed characteristic histopathologic features, including hyperplastic reactive secondary lymphoid follicles with preserved architecture, a marked eosinophilic infiltrate with eosinophilic microabscesses, postcapillary venule proliferation, and patternless stromal fibrosis. Immunohistochemistry demonstrated a raised IgG4:IgG plasma cell ratio of approximately 1:1, with 150–200 IgG4-positive plasma cells per high-power field, raising the differential of IgG4-related disease; however, the absence of storiform fibrosis and obliterative phlebitis, combined with the clinical and serologic profile, favored Kimura disease. This case is notable for its rare epitrochlear location, extensive neural involvement, concurrent diffuse cutaneous eruption, and histopathologic overlap with IgG4-related disease, highlighting the diagnostic challenges posed by atypical presentations of Kimura disease.

Pleomorphic liposarcoma (PLPS) is a highly aggressive sarcoma comprising variable numbers of pleomorphic lipoblasts mixed with undifferentiated pleomorphic sarcoma (UPS)-like areas. Morphologic variants, such as myxofibrosarcoma-like or epithelioid, may cause diagnostic confusion, especially on a core biopsy, but there are few data on the prognostic significance of these features. A total of 120 PLPS biopsies and resection specimens were reviewed and catalogued based on the presence of myxofibrosarcoma-like, UPS-like, and epithelioid foci, in 10% increments. The clinical parameters were collected. Cases occurred in 75 males and 45 females, ranging from 8 to 98 years (median, 62.5 y). Cases arose in the extremities (n=72), trunk (n=32), head/neck (n=10), bone (n=4), mediastinum (n=1), or viscera (colon polyp, n=1). Of those with known depth (n=81), 40 were intramuscular, 34 were subcutaneous, and 7 arose in the dermis. Their sizes ranged from 1 to 24.5 cm (median, 7 cm). Of the patients with ≥1 month of follow-up (n=70), 5 had recurrence and 15 had metastasis. The 5-year overall survival and event-free survival rates were 66.2% and 63.1%, respectively. Tumors ≥5 cm had inferior overall survival compared with tumors <5 cm. The presence of epithelioid areas was also statistically significant in terms of poorer overall survival and event-free survival, while tumors with ≥50% undifferentiated pleomorphic-like areas had better overall survival. There was a trend towards poorer outcomes in tumors with necrosis (≥1%). PLPS is an aggressive adipocytic malignancy that is most commonly present in the extremities of older adults. The morphologic features of these tumors are diverse, and they may be mistaken for UPS or myxofibrosarcoma, carcinoma, and melanomas, particularly on biopsies. Tumor size, necrosis, and epithelioid morphology are associated with adverse prognosis.