[Hypopigmented mycosis fungoide. Case report].

Background: Hypopigmented mycosis fungoide (HMF) is a rare variant of cutaneous T-cell lymphoma of unknown pathogenesis. It is the most common cutaneous lymphoma in childhood. It is characterized by hypopigmented macules in non-photoexposed areas, generally asymptomatic. The diagnosis is confirmed with histopathological study and immunohistochemistry. Treatment will depend on the clinical stage, with topical therapies being the first-line treatment. Clinic case: 69-year-old female, with no significant personal pathological history. She was treated for dermatosis of 7 years of evolution, spread to the 4 segments with affected body surface of 35% that respected palms and soles, characterized by polymorphic hypochromic macules of 1 to 10 cm in diameter that converge to form larger lesions, and some post-inflammatory hyperchromic macules, accompanied by itching. The histopathological study reported data compatible with mycosis fungoides and immunohistochemistry with positivity for CD3, CD4, CD5 and CD8. It was diagnosed stage IB HMF. It was administered treatment based on prednisone and phototherapy with a good response. Conclusions: This case makes possible an outlook of the demographic data of HMF, and it allows this entity to be taken into consideration for possible differential diagnoses that are not contemplated due to the limited dissemination of knowledge about this disease. It is important to emphasize the knowledge of HMF since early diagnosis and timely treatment will improve the prognosis in our patients and prevent them from being treated incorrectly.