The peritoneal carcinomatosis of prostate cancer without bone or other visceral organ involvement is extremely rare. We report a case of an isolated peritoneal metastasis of prostate cancer in a patient without other metastatic sites and a history of prostate surgery. A 63-year-old male with locally advanced prostate cancer without known distant metastasis on androgen deprivation therapy presented with abdominal distension that had persisted for a month. Abdominopelvic computed tomography (CT) showed gastric wall thickening and a moderate amount of ascites. The gastroscopy showed hyperemic mucosal patches on the antrum body. A cytological examination of the ascites fluid was negative for malignant cells. Diagnostic laparoscopy showed multiple nodules in the peritoneum. A biopsy was performed. Histological findings were compatible with metastatic carcinoma of the prostate, which was immunohistochemically positive for pan-cytokeratin, the androgen receptor, and prostate-specific antigen (PSA). The patient was then treated with abiraterone acetate. After 1 month of treatment, both ascites and the PSA value decreased. We describe an extremely rare case of isolated peritoneal carcinomatosis from prostate cancer without any organ metastasis or history of surgery. Clinicians should be aware of these very rare metastases of prostate cancer. Hormonal therapy may be helpful for such cases.

T-large granular lymphocytic leukemia (T-LGLL) is an uncommon clonal lymphoproliferative disorder, predominantly originating from CD8⁺ αβ T cells. γδ T-cell and CD4⁻/CD8⁻ double negative variants are uncommon, with their molecular characteristics and clinical behavior not yet fully elucidated. STAT5B mutations have been reported in specific subsets of T-LGLL and may correlate with aggressive disease in certain variants. We report the case of a 58-year-old woman with persistent lymphocytosis for more than four years. The patient had no B symptoms, lymphadenopathy, hepatosplenomegaly, autoimmune disease, or abnormal inflammatory markers. Peripheral blood contained 3.65 × 10⁹/L large granular lymphocytes (50% of leukocytes), with abnormal lymphocytes accounting for 11.2% of bone marrow nucleated cells. Immunophenotyping demonstrated a γδ CD4⁻/CD8⁻ double negative T-cell population with CD16/CD56 co-expression. T-cell receptor γ gene rearrangement analysis revealed T-cell clonality, while cytogenetic analysis revealed a normal karyotype. Targeted next-generation sequencing of whole bone marrow DNA identified a STAT5B c.1883 C > G (T628S) mutation with a variant allele frequency (VAF) of 6.5%, along with a CCND3 variant of uncertain significance. Despite the STAT5B mutation, the patient remained clinically stable without treatment. Serial complete blood count analyses indicated persistent lymphocytosis without progressive leukocytosis, stable hemoglobin concentrations, and stable platelet counts. This case illustrates that the presence of a STAT5B mutation was not associated with aggressive clinical behavior, as the patient maintained an indolent clinical course.

Hee Ryeong Jang, Kyu-Hyoung Lim. Journal of Digestive Cancer Research 2023;11:119-21. https://doi.org/10.52927/jdcr.2023.11.2.119