Foamy gland microcarcinoma in needle prostatic biopsy

Foamy gland carcinoma is an uncommon variant of prostatic carcinoma. Foamy microcarcinoma of the prostate has not been studied in detail in needle biopsy. We describe here useful criteria for the diagnosis of foamy gland microcarcinoma of the prostate in needle biopsy. We reviewed 6 cases of foamy gland microcarcinoma. All tumors measured less than 1 mm and involved less than 5% of the biopsied tissue. A range of 4 to 40 foamy neoplastic glands were found in the 6 tumors. The original diagnosis of foamy gland microcarcinoma was made in 3 cases. They were composed of 21 to 40 glands lined by cuboidal to columnar cells with abundant foamy cytoplasm and small picnotic nuclei. Infiltrating and nodular patterns were readily identified, and absence of basal cells was shown by cytokeratin stains. The remaining 3 cases were designated as atypical foamy glands and consisted of similar but fewer glands (4-20). The diagnosis of foamy gland microcarcinoma was not made because of lack of nucleomegaly and prominent nucleoli and because an infiltrating pattern was less apparent. Subsequent biopsies confirm the diagnosis of microcarcinoma. The number of glands lined by voluminous foamy cells with hyperchromatic nuclei, an infiltrating pattern, and the absence of basal cells with high-molecular-weight cytokeratin were the most useful features in the diagnosis of foamy microcarcinoma. The presence of few atypical foamy glands in needle biopsy requires detailed analysis because they may represent foamy gland microcarcinoma.