Clinical Findings: An 80 years old man initially developed a groin rash for 10 days and he visited a dermatologist. The groin lesion was thought to be fungal infection, but dermatologist also noticed a few other lesions on his eyelid, forehead, and right flank and these lesions were biopsied. The clinical impression was rule out cancers. For the flank lesion, an id reaction, an urticaria, or a drug was suggested. This patient has been taking multiple medications, otherwise his medical history of malignancy was unremarkable.
Pathological Findings: Multiple biopsies from different site showed various range of dermal mononuclear cell infiltrate from a subtle perivascular infiltration to a pandermic dense infiltration. At low magnification, a stary-sky pattern due to increased number of tingible body macrophages indicated an increased cellular turn-over rate in this tumor. The presence of frequent extravasated red blood cells could be responsible for the erythematous clinical appearance. Tumor cells were intermediate cells with fine chromatin and inconspicuous nucleoli, consistent with blast morphology. Subset of tumor cells showed cleaved nuclear membrane, which can be frequently seen in monoblast population. Frequent mitosis was also observed. Immunohistochemical studies showed that the tumor cells were positive for CD4, CD56, and lysozyme. The tumor cells were negative for MPO, CD3, CD8, CD20, CD30, CD1a, CS123, and TLC-1. Ki67 indicate a high cell proliferative activity.
Follow-Up: Up to date (22 months since diagnosis), he has not had any other new skin lesions or any recurrence of these skin lesions. His bone marrow has been clear and his peripheral counts have been very steady. He is currently absolutely asymptomatic.