Prostate Cancer Associated with Muir-Torre Syndrome: A Rare Case Report and Literature Review.

Abstract

Introduction: Muir-Torre syndrome (MTs) is a rare autosomal dominant disorder characterized by sebaceous neoplasms and internal malignancies, most commonly colorectal and urothelial cancers. Prostate cancer is exceptionally rare in MTs, with only thirteen cases reported to date.

Case presentation: We present the case of a 65-year-old male initially diagnosed with MTs following the development of multiple sebaceous tumors and identification of a heterozygous MSH6 mutation. Immunohistochemistry demonstrated isolated loss of MSH6 protein expression, with preserved microsatellite stability - an unusual finding in MTs. Despite two negative prostate biopsies and a transurethral resection, choline positron emission tomography imaging revealed hypermetabolic pelvic and cervical lymph nodes. Excisional biopsy confirmed metastatic prostate adenocarcinoma (NKX3.1-positive). The patient received first-line androgen deprivation therapy with an LH-RH analog and apalutamide, achieving a sustained biochemical response. He remained alive and on treatment with undetectable PSA 3 years later, at the age of 74.

Conclusion: This case highlights the diagnostic challenges of prostate cancer in MTs and the need to consider metastatic disease in atypical presentations, especially when MMR deficiency is suspected.