A 76-year-old man was admitted to the hospital with an increase in overall weakness. However, the patient could not be recognized by the hospital staff because of a pronounced change in his skin colour which occurred several weeks ago. Moreover, the patient had developed a progressive, gray-blue discolouration of the skin. However, the white patient was no longer the same person as on his identity card. 14 months ago, the patient was diagnosed with a malignant melanoma but was negative for BRAF mutation.
In addition to this, 5 months earlier, the melanoma had metastasised to the patient’s liver and spleen. The patient received four cycles of dacarbazine after the metastases was detected. Likewise, the hyperpigmentation of the patient’s skin that made him completely unrecognizable was a presenting symptom of diffuse melanosis cutis. Melanosis cutis is considered a worrying sign and is associated with a median survival of only up to 6 months. However, fortunately, the patient survived for an additional 16 months after development of melanosis cutis. The patient was put under immune therapy with ipilimumab.
What is melanosis cutis?
Melanosis cutis is a rare presentation of metastatic melanoma. In this condition, the entire colour of the surface of the skin changes. Approximately 1 to 2 percent of patients with metastatic melanoma are affected with melanosis cutis. Although, the exact pathophysiology of the underlying diffuse melanosis is unknown. A theory suggests that it may be caused because of circulating melanin precursors released by melanoma cells. The melanoma cells enter the dermis and undergo auto-oxidisation to melanin with dermal extracellular fluid and dermal histiocytes.
Melanosis cutis presents with clinical features including a progressive blue-gray discolouration of the entire skin and mucous membrane. The discolouration typically occurs over the time span of weeks or months. It is also associated with darkening of urine, malanuria which becomes more pronounced as the urine stands.
Jansen, T., & Hoff, N. P. (2016). Diffuse melanosis cutis. New England Journal of Medicine, 374(12), 1177-1177.