Histiocytic medullary reticulosis with parallel increases in serum acid phosphatase and disease activity

Two months after presenting with autoimmune hemolytic anemia, a 57-year-old man developed increased serum acid phosphatase activity. Subsequently, abnormal histiocytes were found in the bone marrow and blood, and 8 months after the onset of his illness lymph node biopsy led to the diagnosis of histiocytic medullary reticulosis. At that time the level of serum acid phosphatase activity was more than 60 times the upper limit of normal and then paralleled the activity of his disease during temporary responses to chemotherapy, rising to over 90 times normal at the time of his death 1 year after presentation. No prostatic malignancy was demonstrated by biopsies or at autopsy, and electrophoretic studies of the serum enzyme suggested that it was of extraprostatic origin. It is postulated that the acid phosphate present in the serum at levels heretofore described only in metastatic carcinoma of the prostate may have arisen from the abnormal histiocytes.