This edition is devoted to difficult entities of the prostate, with the hope to provide practical guidance and differential diagnoses for pathologists and residents. For many, prostate biopsies are among the “bread and butter”–type specimens that are encountered on a daily basis. While in most cases the diagnosis may appear straightforward, awareness of unique clinical scenarios and mimickers may help pathologists avoid diagnostic pitfalls.
The first group of articles discuss challenges in diagnosing hormone-treated prostate cancer, a frequently encountered specimen for many pathologists. Burke et al. provide an organized approach to the morphologic spectrum of castration-resistant prostate cancer with several case reports. Continuing on this topic, Ye et al describe an interesting and diagnostically challenging case: a hormone-resistant prostatic carcinoma mimicking a prostatic basal cell carcinoma. Additionally, mixed acinar-neuroendocrine prostatic carcinomas are among the most clinically relevant histologic patterns for practicing pathologists to recognize; an example is provided by Cordeiro-Rudnisky et al. Finally, a case of hormone-treated prostate cancer with immunohistochemical neuroendocrine expression and a review of neuroendocrine expression in prostate cancer are presented by Russell et al.
The next group of articles centers on interesting cases of variant histology in treatment-naive patients. Long et al. report a prostatic adenosquamous carcinoma presenting as a metastasis. Yang and Sun describe an unusual case of a patient with hypogonadism on exogenous hormone replacement presenting with features of treated prostate cancer. Prostatic carcinoma with aberrant expression of p63, a unique variant of prostatic carcinoma, is discussed by Paulk et al.
Samarska and colleagues describe 2 prostatic rhabdomyosarcomas and provide a useful review of the differential diagnosis in prostatic soft tissue tumors.
Rare but important benign mimickers of malignancy are presented by Chen et al, who describe prostatic malakoplakia and histiocytic lesions, and Legesse et al, who present 2 cases of prostatic blue nevus, a rare entity that may be misdiagnosed as malignant melanoma.
We are thankful to all of the authors for their contributions to this edition and to the editors for allowing us the opportunity to compile this material.