Retinoids are a group of substances comprising vitamin A and its natural and synthetic derivatives. Retinoids were first used in dermatology in 1943 by Straumfjord for acne vulgaris. Since that time, retinoids have been utilized in the management and treatment of various skin conditions, including photoaging. Photodamage of the skin occurs as a consequence of cumulative exposure to solar ultraviolet radiation (UVR) and is characterized by deep wrinkles, easy bruising, inelasticity, mottled pigmentation, roughness, and telangiectasias. The mechanism of UVR-induced photodamage is multifactorial. Retinoids have demonstrated efficacy in the treatment of photoaged skin. Indeed, understanding the pathophysiology of photoaging and the molecular mechanism of retinoids can not only provide insight into the effects retinoids can exert in treating photoaging but also provide the rationale for their use in the treatment of other dermatologic diseases.
Approximately 5% of oncology patients develop cutaneous metastases, with only a small number of these patients (less than 1%) having metastatic skin lesions as the first sign of their visceral cancer. Metastases tend to occur on skin surfaces in the vicinity of the primary tumor. However, any site may be affected by cutaneous metastases. Skin metastases can present with several morphologies including, albeit rarely, keratoacanthoma-like lesions. Keratoacanthoma is a keratinous tumor that morphologically appears as a nodule with a central keratin-filled crater. This article reviews the characteristics of oncology patients whose cutaneous metastases mimicked a keratoacanthoma, including illustrations from our patient, a 53-year-old Caucasian man whose metastatic esophageal adenocarcinoma not only presented with a keratoacanthoma-like tumor on his upper lip but also a forehead macule and a scalp nodule. We also report keratoacanthoma-like presentations from literature cases of breast cancer, chondrosarcoma, and pulmonary malignancies. The lesions were discovered 3-24 months after diagnosis of visceral cancer and led to the discovery of unsuspected lung cancer in two patients. Most of the patients (60%) died within 2 months of discovery of the keratoacanthoma-like cutaneous metastases. We also reviewed the literature and discuss other morphologies of cutaneous metastases in patients whose primary tumors were in the breast, lung, and esophagus. In addition, we review from the literature other examples of tumors that present as metastatic nodules on the scalp. The possibility of cutaneous metastasis should be entertained and pathologic evaluation should be considered in an oncology patient with underlying visceral malignancy who develops a keratoacanthoma-like lesion.
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