Cutaneous metastases of internal malignancies: an experience from a single institution.

Background: Cutaneous metastases represent 2% of all skin tumours. Their recognition can be challenging, as they may present with different clinical features, with consequent frequent delay and failure in diagnosis.

Objectives: To review our series of cutaneous metastatic lesions, analyse their frequency according to patient gender, histotype, localization of the primary tumour, and site of cutaneous metastasis, and correlate this data with clinicopathological parameters.

Materials & Methods: We conducted a retrospective review of all cases of cutaneous metastases from visceral neoplasms diagnosed in our dermatopathology department from July 2003 to February 2017. We registered clinical, histological, and immunohistochemical data. Additional immunohistochemical staining panels were elaborated to confirm or identify the origin of the primary tumour, or at least to specify the histological subtype.

Results: We identified 45 histological diagnoses of cutaneous and mucocutaneous metastases. The primary tumour that was most likely to metastasize to the skin was breast cancer. Most cases of breast (89%) and lung cancer (86%) metastasized to the trunk. Of the lesions, 57.5% were nodules and 32.5% were plaques, more frequently multiple (64.4%). In 58% of cases, a metastasis was clinically suspected. Histological examination most frequently revealed an adenocarcinoma, sometimes suggestive of the site of origin.

Conclusions: Cutaneous metastases should be primarily considered when discrete firm painless nodules emerge rapidly. Clinicians should carefully consider infiltrated lesions of the chest in women since scleroderma and erysipelas-like presentation can be a clue for undiagnosed breast cancer.