High-grade Foamy Gland Prostatic Adenocarcinoma on Biopsy or Transurethral Resection A Morphologic Study of 55 Cases

Foamy gland carcinoma is a variant of adenocarcinoma of the prostate that typically is assigned a Gleason score 3 + 3 = 6. The morphologic features of high foamy gland carcinoma have not been previously studied. We analyzed 55 cases of high-grade (Gleason score 7 or greater) foamy gland carcinoma of the prostate in needle biopsy (n = 49) or transurethral resection (n = 6) specimens. The number of cores involved by high-grade foamy gland carcinoma ranged from I to 12, with more than 1 core involved in 61% of cases (mean 3.4 cores). On average. 84% of the total tumor volume was foamy Gland carcinoma, with high-grade foamy gland cancer averaging 73% of the total foamy gland carcinoma. The following results pertain only to the high-grade foamy gland cancer component. The most common architectural pattern was cribriform (73%). followed by fused/poorly defined glands (55%), cords/single cells (11%). and solid sheets (5%). Nuclear enlargement was observed in 45 of the 55 studied cases (82%). Prominent nucleoli were either absent or infrequent in 38 cases (69%). Frequent to numerous prominent nucleoli were seen more frequently in foamy gland carcinoma with Gleason score 8 or above (52%) than those with Gleason score 7 (16%) (P < 0.004). Mitotic figures were observed in 22 cases (40%). and present in 65% of the cases with Gleason score 8 or above, but only in 22% of the cases with Gleason score 7 (P < 0.002). In 31 cases (56%). intraluminal dense pink secretions were identified. Perineural invasion and extraprostatic extension identified on the biopsy specimens were noted in 18 cases (33%) and in 5 cases (9%), respectively. In IS cases (33%), there was at least a moderate stromal reaction. A moderate or greater stromal reaction was seen in 48% (11/23) of the cases with Gleason score 8 or above compared with 22% (7/32) of the cases with Gleason score 7 (P = 0.04). In 6 cases, there was a peculiar extensive desmoplastic reaction almost obscuring the carcinoma component, 5 of which were Gleason scores 4 + 4 = 8. Concurrent ordinary acinar nonfoamy adenocarcinoma was encountered in 26 of 55 cases (47%) with the following Gleason scores: Gleason 6 (27%); Gleason 7 (27%); and Gleason 8 to 10 (46%). Associated ordinary high-grade prostatic intraepithelial neoplasia and