Cutaneous metastases from visceral malignancies mimicking interstitial granulomatous processes: a report of 3 cases.

There are multiple clinical and histopathologic presentations of cutaneous metastases. We report 3 cases of visceral malignancies metastasizing to the skin and histopathologically mimicking interstitial granulomatous processes, including granuloma annulare and interstitial granulomatous dermatitis. Histopathologic examination of skin biopsy specimens, from our patients with established histories of cancer, revealed malignant carcinoma-derived cells organized in an interstitial pattern. Of note, some of the lesional cells appeared relatively bland without significant cellular atypia. When examining a skin biopsy of a new lesion from a patient with a history of internal malignancy, it is important to perform immunohistochemical staining to evaluate for metastatic disease, even if the histological pattern is suggestive of a benign interstitial granulomatous process.