Paneth cell-like change in prostatic adenocarcinoma represents neuroendocrine differentiation: report of 30 cases

Paneth cell-like change (PCLC) of the prostatic epithelium is considered to be a distinct form of neuroendocrine differentiation characterized by isolated cells or small groups of cells with prominent eosinophilic cytoplasmic granules. We evaluated 300 serially sectioned radical prostatectomy specimens from patients with prostatic adenocarcinoma who had not received prior adjuvant therapy (pathologic stages T2NOMO [177 patients], T3NOMO [100 patients], and TxN1MO [23 patients]). Paneth cell-like change was identified in 30 cases (10%), ranging from 1 to 20 high-power fields/positive case (mean, 4.1 high-power fields/case). There was no correlation of PCLC with prostate volume, prostate weight, Gleason grade, nuclear grade, lymph node metastases, serum prostate-specific antigen levels, cancer volume, area or presence of capsular perforation, seminal vesicle invasion, or glandular mucin (all P > .05), although a positive correlation was seen with cribriform pattern (r = 0.50, P = .0015). Immunohistochemistry revealed cytoplasmic immunoreactivity within cells of PCLC for chromogranin (seven of seven cases), neuron-specific enolase (seven of seven cases), serotonin (six of seven cases), prostate-specific antigen (five of seven cases), and prostatic acid phosphatase (four of seven cases); lysozyme was negative (seven cases). Our findings indicate that PCLC is more common than previously reported, but that it is not associated with tumor grade, serum PSA levels, or pathologic stage. This study also shows that PCLC represents neuroendocrine differentiation, suggesting that the term "Paneth cell-like change" be deleted from the pathologist's lexicon in relation to prostatic adenocarcinoma; a more appropriate term might be "neuroendocrine cells with large eosinophilic granules."