[923] High Grade Foamy Gland Prostatic Adenocarcinoma on Biopsy or Transurethral Resection: A Morphological Study of 55 Cases

J Zhao, JI Epstein. Johns Hopkins Hospital, Baltimore

Background: Foamy gland carcinoma is a variant of adenocarcinoma of the prostate that typically is assigned a Gleason score 3+3=6. The morphological features of high foamy gland carcinoma have not been previously studied.
Design: We analyzed 55 cases of high grade (Gleason score 7) foamy gland carcinoma of the prostate in needle biopsy (n=49) or TURP (n=6).
Results: On average, 3.4 cores were involved by high grade foamy gland carcinoma. 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 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 82% of cases. Prominent nucleoli were either absent or infrequent in 69% of cases, and seen more frequently with Gleason score 8. Mitotic figures were observed in 40% of cases, more frequently in Gleason score 8. In 56% of cases, intraluminal dense pink secretions were identified. Perineural invasion and extraprostatic extension identified on the biopsy specimens were noted in 33% and 9% of cases, respectively. In 33% of cases, there was at least a moderate stromal reaction. 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 non-foamy adenocarcinoma was encountered in 47% of the cases: Gleason 6 (27%); Gleason 7 (27%); and Gleason 8-10 (46%). Of the 19 cases with available immunohistochemical stains for high molecular weight cytokeratin, 7 (37%) showed nonspecific labeling of cancer cells in a non-basal cell pattern. A similar finding was seen in 1 of the 7 (14%) of the cases with available stains for p63. -Methyl-CoA racemase (AMACR) positivity was noted in all 9 cases stained.
Conclusions: High grade foamy gland cancer shares certain morphological features with more typical lower grade foamy gland cancer including relatively bland nuclei with more difficult to identify nucleoli as well as frequent intraluminal dense pink secretions. However, consistent with their higher architectural grade, high grade foamy gland cancers had more prominent nucleoli and increased mitotic figures compared to lower grade foamy grade cancer. A unique subset of high grade foamy gland carcinoma poses particularly difficult diagnostic challenges, with scattered, scant, relatively bland foamy glands imbedded in an extensive densely sclerotic desmoplastic stroma.
Category: Genitourinary (including renal tumors)

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 128, Tuesday Afternoon