Diagnostic Challenges in Identifying Concurrent Myeloid Sarcoma and High-Grade Prostatic Adenocarcinoma Within the Prostate

Myeloid sarcoma is an extramedullary mass lesion composed of myeloid blasts that disrupt tissue architecture. Myeloid sarcoma in the prostate is exceptionally rare, with fewer than 30 patients reported. Among these, 8 have been observed without a prior diagnosis of a hematolymphoid neoplasm. To date, concurrent prostatic myeloid sarcoma and adenocarcinoma have not been documented in the English-language literature. We present the first 2 myeloid sarcomas in the prostate occurring concurrently with high-grade prostatic adenocarcinoma, identified on core needle biopsy and radical prostatectomy in patients without a prior history of myeloid sarcoma or acute myeloid leukemia (AML), and highlight the associated diagnostic challenges. Both were positive for NPM1 by immunohistochemistry, consistent with <i>NPM1</i> mutation. Neither patient received treatment for myeloid sarcoma/AML due to multiple comorbidities. One patient succumbed to the disease 44 days after diagnosis, while the other passed away from respiratory failure in the context of multiple comorbidities 2 months after being diagnosed with myeloid sarcoma.