High-Grade Desmoplastic Foamy Gland Prostatic Adenocarcinoma

It is important to recognize high-grade foamy gland prostatic adenocarcinoma with desmoplastic stroma given its aggressive clinical course with frequent metastases and death.

To review the morphology, immunohistochemistry, and prognosis for this rare subtype of prostate adenocarcinoma.

Twenty-four cases received for consultation from 2010 to 2021 were analyzed including needle biopsy (n = 21), transurethral resection (n = 2), and a cystoprostatectomy (n = 1).

Patients ranged in age from 40 to 89 years (mean, 67 years). On average, 8 cores per case were involved (mean 67% core involvement). Extraprostatic extension and seminal vesicle invasion were observed in 6 of 21 (29%) and 3 of 21 (14%) needle biopsy cases, respectively. Twenty of the 24 cases (83%) were Grade Group (GG) 5 with 4 of 24 (17%) being GG4. Tumor necrosis as a component of Gleason pattern 5 was observed in 21 of 24 cases (88%). Associated intraductal adenocarcinoma (IDC) was observed in 22 of 24 cases (92%), with 4 of 24 cases (17%) demonstrating extensive IDC. Diagnostic challenges were as follows: (1) sparse isolated cancer glands embedded in the dense desmoplastic stroma; (2) fragmented glands; and (3) aberrant staining for high-molecular-weight cytokeratin in a nonbasal cell pattern in all cases. PTEN loss was observed in 9 cases, and p53 nuclear accumulation was observed in 8 cases. Three patients were lost to follow-up. Overall, of the 16 patients with meaningful follow-up, 12 (75%) either had metastases or died from prostate cancer.

High-grade desmoplastic foamy gland adenocarcinoma is difficult to diagnose and grade and has a poor prognosis.