Histopathologic examination showed an atypical cellular infiltrate along the base of the epidermis, with focal pagetoid extension into the epidermis and a heavy dermal infiltrate of similar cells. The pattern of tumor, absence of staining for cytokeratin 20, positive results on staining with periodic acid–Schiff after diastase digestion, and positivity for CAM 5.2, epithelial membrane antigen, and cytokeratin 7 strongly supported the diagnosis of EPMD.
Additional investigations were undertaken because of the association of EMPD with internal malignancy. The findings of chest radiography, urine microscopy, culture, and cystoscopy were normal. Ultrasound of the prostate showed no focal lesion. Ultrasound of the groin revealed extensive lymphadenopathy in the right side of the groin, with the largest lymph node measuring 3.9 cm in diameter. Computed tomography of the abdomen and pelvis demonstrated extensive lymphadenopathy along both sides of the abdominal aorta, pelvic side walls, and groin; the kidneys, liver, spleen, and pancreas were unremarkable. A fine-needle aspirate of a lymph node showed necrotic cellular debris, a finding that is highly suggestive of metastatic carcinoma. Examination of an excised lymph node showed replacement of normal architecture by an infiltrate that was similar to the cutaneous infiltrate, with an identical immunoprofile, confirming the diagnosis of metastatic carcinoma. The primary cell of origin was unknown.
Nodule on the Penis—Diagnosis. Arch Dermatol. 2006;142(4):515-520. doi:10.1001/archderm.142.4.515-b