P01 Pigmented and purpuric patches in sun protected areas of a 9 year old child

Abstract

Abstract Pigmented purpuric dermatosis-like mycosis fungoides (PPD-like MF) is a rare variant of paediatric mycosis fungoides (MF). Clinically, it can be challenging to diagnose and differentiate from pigmented purpuric dermatosis (PPD). Usually, has an indolent course if diagnosed in the early stage. The lesions often localize to sun-protected areas with three stages: patch, plaque, and tumour. Clinical features alone are insufficient for diagnosis and a skin biopsy is mandatory.1 We report a nine year old boy who presented with a three year history of a persistent, slowly progressing, mildly pruritic and scaling rash on the right buttock and medial thighs bilaterally. He was otherwise well with no other relevant medical or family history of note. The physical examination revealed erythematous to purpuric, mild scaly patches with confluent involvement on the right buttock extending to less defined involvement of the both inner thighs. The body surface area involved was less than <10%. No other clinical findings on examination. A punch biopsy for haematoxylin and eosin (H&E) staining was consistent with mycosis fungoides. T cell receptor gene rearrangement testing detected a monoclonal T-cell population. A diagnosis of pigmented purpuric dermatosis-like mycosis fungoides was made. The patient responded well to a potent topical steroid (mometasone furoate) daily which was gradually tapered to twice weekly/intermittent usage to maintain response.