Phacomatosis pigmentokeratotica (PPK) is a rare epidermal nevus syndrome characterized by the co-occurrence of a nevus sebaceous arranged along the lines of Blaschko with a speckled lentiginous nevus (SLN). We report a novel KRAS mutation in a patient with a large nevus sebaceous and an SLN who subsequently developed a vaginal botryoid rhabdomyosarcoma, an association not previously reported in the literature. This case expands our knowledge of the genetic basis for phacomatosis, in which mutations in HRAS have been previously described, although this report provides evidence that activating mutations in KRAS or HRAS may cause PPK. This report confirms that PPK is a mosaic RASopathy with malignant potential and raises the question of whether screening for other RAS-associated malignancies should be performed for all children with PPK.

Physicians should be aware that GAP can occur without NSF or renal disease and is associated with the use of radiologic dyes. Sclerotic bodies have been reported only in association with gadolinium exposure (eg, gadodiamide) either in the sclerotic skin in NSF or in GAP.

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Melanoma-associated leukoderma (MAL) is a relatively uncommon phenomenon in the literature that can present (1) before melanoma detection, (2) after detection and before treatment, and (3) after treatment with immunotherapeutic agents. We report a case of MAL in an 83-year-old man after treatment with high dose IL-2 for metastatic melanoma and further describe the literature of the underlying mechanisms behind it that involve the immune system. Cytotoxic CD8+ T cells are thought the mediate the process at a cellular level. Self-antigens (e.g. MART-1/2, gp100, tyrosinase) have been presented on the surface of both normal and malignant melanocytes and mediate the development of MAL after cytotoxic CD8+ T cells attack both cell types. Autoimmune manifestations have a positive effect on tumor immunity, with patients at stage III and stage IV melanoma showing a better prognosis after leukoderma development. In addition, immunotherapy induced leukoderma has been associated with a higher therapeutic response rate. Recently, newer immuno-therapeutic drugs, such as vemurafenib and ipilimumab, have been associated with leukoderma as a side effect.