Tumoral calcium pyrophosphate dihydrate deposition disease: cytopathologic findings on fine-needle aspiration.

Tumoral calcium pyrophosphate dihydrate deposition disease (CPPD) is a rare non-neoplastic entity which mimics primary or metastatic soft-tissue or skeletal malignancy. Fewer than a dozen cases have been reported in the literature with only histologic descriptions. We present cytologic findings of a unique case of CPPD in a 73-year-old black female with a history of end-stage renal disease. A fine-needle aspiration (FNA) was done on a 4 x 4-cm neck mass which was clinically thought to be malignant. Cytopathologic examination showed numerous macrophages with markedly distended cytoplasm and containing multiple yellowish-orange, short rhomboid crystals. These were strongly birefringent on polarized microscopy, consistent with CPPD crystals.