Multiple Low-Grade Fibromyxoid Sarcoma on the Upper Arms with Atypical Histological Presentation
A 61-year-old Japanese female presented to our clinic with an 8-month history of asymptomatic subcutaneous nodules on her arm. On her first visit to our outpatient clinic, physical examination revealed an elastic, hard subcutaneous nodule on her bilateral upper arms (fig. ). The nodules were approximately 25 mm in diameter. We excised two nodules and histological findings revealed degenerated collagen fibers and necrosis, surrounded by histiocytes and partially palisaded granuloma-like bodies (collagen rosettes) (fig. ). We observed spindle-shaped cells that had eosinophilic cytoplasm, with no nuclear atypia or mitotic activity (fig. ). Mucin deposition was prominent at the centers of the granuloma-like bodies (fig. ). We diagnosed this tumor as a subcutaneous type of granuloma annulare or myxofibroma. One year later, the patient noticed a subcutaneous nodule on her left arm and we excised the nodule again. Histological findings were similar to those of the previous lesion. A half year later, a subcutaneous nodule, 20 mm in diameter, appeared on her left arm near the operative area. Then, we screened for a possible internal malignancy with positron emission tomography but found none. We excised the nodule again below the muscle fascia, and the histopathological findings revealed myxoedematous proliferation, degenerated collagen fibers and necrosis, surrounded by lymphocytes, histiocytes and multinucleated giant cells in the dermal to subcutaneous area (fig. ). Alcian-blue PAS staining revealed mucin deposition at the center of the tumor. From the above data, we diagnosed this tumor as LGFMS. Two years after the last excision, there was no sign of recurrence or metastasis.