Multiple Red Nodules on Lower Abdomen

REPORT OF A CASE A 71-year-old man was referred for evaluation of an asymptomatic skin eruption that had been present on the lower aspect of his abdomen for approximately 10 weeks. The physical examination revealed innumerable 2- to 3-mm, firm, freely moveable, violaceous deep papules and about 12 3- to 10-mm exophytic, firm, orange-to-red hairless papulonodules (Fig 1). The lesions were limited to the lower abdominal, suprapubic, and inguinal skin. Routine hematologic and biochemical tests showed normal findings except for mild anemia (hemoglobin, 110 g/L; hematocrit, 0.34). Serum acid phosphatase and carcinoembryonic antigen levels were mildly elevated. A punch biopsy specimen was obtained from a typical lesion. Histologic findings are depicted in hematoxylin-eosin-stained sections (Figs 2 and 3). Immunohistochemical staining for acid phosphatase is shown in Fig 4. What is your diagnosis? DIAGNOSIS: Metastatic carcinoma of the prostate. HISTOPATHOLOGIC FINDINGS The biopsy specimen revealed infiltration of the dermis by islands of cells arranged in a glandular fashion consistent with