Splenic metastasis in hairy cell leukemia

Background. Splenic metastasis is uncommon and usually occurs in the setting of widespread visceral metastasis. Splenic metastasis as an initial manifestation of disease and sole site of metastasis has not been reported previously. Methods. The authors describe a patient with hairy cell leukemia (HCL) with the unexpected finding of metastatic adenocarcinoma in the spleen. Direct inspection at the time of laparotomy and subsequent radiographic studies did not show a primary or additional metastatic tumor. Eventually, he manifested evidence of pulmonary and hepatic metastases and died with fungal sepsis. Results. The splenectomy specimen showed HCL and metastatic adenocarcinoma. Immunohistochemical studies showed adenocarcinoma with diffuse cytoplasmic staining for prostate‐specific antigen and focally positive results with prostatic acid phosphatase antigen. Postmortem examination 9 months later showed HCL and widespread metastatic adenocarcinoma. No primary tumor was identified, and multiple tissue blocks of the prostate had negative findings for tumor. Conclusions. The immunohistologic features of the metastatic adenocarcinoma were interpreted as prostatic in origin. The pattern of isolated metastatic disease in the absence of primary tumor appears to represent another possible atypical disease presentation of prostatic cancer. Hairy cell‐induced structural and immunologic alterations within the splenic microenvironment may have contributed to this unique clinical presentation.