Prostate Adenocarcinoma With Collagenous Micronodules.--When one encounters collagenous micronodules, an intracellular eosinophilic material also considered a specific feature for prostate cancer, one should try to subtract this feature from the analysis and grade the tumor on the basis of its underlying architecture.
Gleason Grading of Unusual Subtypes and Patterns of Prostate Cancer Histologic Type or Pattern Gleason Grade Foamy gland pattern Graded by underlyingarchitecture Pseudohyperplastic 3 Atrophic 3 Large duct carcinoma 4;with evidence of necrosis, 5 Signet ring cell carcinoma 5 Small cell carcinoma Not graded Adenosquamous and squamous Not graded carcinoma Sarcomatoid carcinoma Not graded Glomeruloid pattern 3 or 4 Collagenous micronodules Usually 3, graded by underlying architecture (subtract collagenous micronodules from analysis) Mucinous (colloid) carcinoma 3 or 4, graded by underlying architecture
The incidence of the following features was analyzed in cancerous and noncancerous epithelium in each case: prominent nucleoli, multiple nucleoli, nucleolar margination, intraluminal crystalloids, intraluminal basophilic mucin, intraluminal amorphous eosinophilic material, collagenous micronodules, glomerulations, retraction clefts, perineural invasion, and glands infiltrating adipose tissue.
(15) Collagenous micronodules and glomerulations were identified as described in the literature.
Like glomerulations, collagenous micronodules were not observed in any of the benign biopsies, being found in 3 (2%) cases of cancer (Figure 6).
Collagenous micronodules are another relatively recently described histologic observation in prostate cancer.
However, as noted by Baisden et al, (13) collagenous micronodules are very rarely the key feature in the diagnosis of limited cancer.
In contrast, some features in which statistical significance was not found (ie, fat invasion or collagenous micronodules), when present, are practically diagnostic of carcinoma in an individual case.