A Rare Case of Prostate-Specific Antigen–Producing Metastatic Parotid Adenocarcinoma Developing Androgen Receptor Resistance

Abstract

A 62-year-old man presented with a rising serum concentration of prostate-specific antigen (PSA) to 53.3 ng/mL (to convert to mg/L, multiply by 1) and a PSA doubling time of 2.6 months. Computed tomography, fluorodeoxyglucoseepositron emission tomography, and C-11 choline positron emission tomography demonstrated a parotid mass with innumerable lytic bone lesions and diffuse metastatic disease to the neck and mediastinal lymph nodes. Mediastinal lymph node biopsy revealed salivary ductal adenocarcinoma that produced PSA and demonstrated androgen receptor sensitivity. The patient had a prolonged clinical benefit to firstand second-line hormone therapy, and his PSA levels correlated with treatment response, development of hormone resistance, and progression. In summary, urologists, pathologists, and primary care providers should be aware that a rising PSA level in the setting of a head and neck mass in a patient without a history of prostate cancer does not constitute a diagnosis of metastatic prostate adenocarcinoma and that other primary tumors should be considered and a broader imaging and pathologic evaluation is indicated.

Prostate‐specific antigen: An unfamiliar protein in the human salivary glands

“…Immunohistochemically, PSA was detected in some human exocrine glands, as mammary gland, acinar pancreatic cells, thyroid gland, uroepithelial cells, periurethral glands, and Skene glands, known as the female prostate (Andrews et al., 2020 ; James et al., 1996 ; Tazawa et al., 1999 ; Van Krieken, 1993 ), as well as in various tumors (Olsson et al., 2005 ). The presence of PSA was also described in several body fluids, such as serum, urine, and milk (Diamandis & Yu, 1997 ; Yu & Diamandis, 1995 ).…”