Key result
A case of alveolar soft part sarcoma presenting as a frontal lobe metastasis demonstrated strong CD68 immunoreactivity and lacked characteristic crystalline inclusions, confirmed by ASPSCR1-TFE3 fusion.
Case Report (n=1)
Reports a rare case of crystal-deficient, CD68-positive alveolar soft part sarcoma presenting as a brain metastasis.
May prompt molecular confirmation of ASPS in atypical CD68-positive brain metastases; extends the recognized histologic spectrum of this tumor.
We report a case of alveolar soft part sarcoma (ASPS) presenting as an isolated frontal lobe metastasis. The tumor demonstrated little or no immunoreactivity for a broad panel of antibodies yet strong, diffuse immunoreactivity with CD68. On electron microscopy, the characteristic rectangular to rhomboid crystalline inclusions of ASPS were not present. Electron-dense granules resembling peroxisomes were present, sometimes in association with elongated granular structures having a periodic, lattice-like arrangement. Metastatic ASPS was confirmed by demonstration of an ASPSCR1-TFE3 fusion and imaging studies that excluded metastatic Xp11.2 translocation renal cell carcinoma. The primary site was subsequently identified in the lower extremity.
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Cykowski et al. (2014) conducted a case report in Alveolar soft part sarcoma (ASPS) brain metastasis (n=1). A case of alveolar soft part sarcoma presenting as a frontal lobe metastasis demonstrated strong CD68 immunoreactivity and lacked characteristic crystalline inclusions, confirmed by ASPSCR1-TFE3 fusion.
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