Hypopigmented Mycosis Fungoides Presenting as a Single Large Patch in a Middle-Aged Woman – An Unusual Presentation

Hypopigmented mycosis fungoides (HMF) is a rare variant of mycosis fungoides which presents as achromic lesions commonly affecting adolescents. A 50-year-old female presented with a single large atrophic hypopigmented patch of size 30 cm × 20 cm over inner aspect of the right upper thigh of 2 years duration. Histopathology showed prominent basilar epidermotropism with lymphoid cells invading the spinous layer; immunohistochemistry staining showed CD3, CD5 and CD8 positivity. The case was diagnosed as HMF and treated with narrowband ultraviolet B phototherapy, methotrexate 10 mg/week and betamethasone dipropionate 0.05% cream resulting in moderate clinical improvement. Assessment at 24 weeks showed no progression of disease. The present case highlights atypical HMF presenting with a single diffuse hypopigmented patch in a 50-year-old female. Although the prognosis for HMF is good, it has malignant potential and should always be treated optimally with long-term follow-up.