INTRODUCTION
The resemblance of mycosis fungoides (MF) to prevalent skin disorders such as atopic dermatitis presents a diagnostic challenge for dermatologists. Histopathologic criteria may demonstrate a lichenoid infiltrate mixed with coarse bundles of collagen in the superficial dermis. MF palmaris et plantaris (MFPP) is a rare variant of MF limited to the palms and soles of the feet. The rarity of this condition further complicates its differentiation from more widespread and visually similar conditions. We present a case of a middle-aged woman with MFPP whose presentation was originally assumed to be dyshidrotic eczema.
CASE PRESENTATION
Patient History
A 56-year-old female with Fitzpatrick skin type V presented with a two-year history of pruritic eczematous plaques affecting her hands and feet. In 2018, the eczematous plaques had been classified as dyshidrotic eczema and treated initially with triamcinolone ointment and then with clobetasol ointment. The lesions were largely unresponsive to both treatments. The patient returned to the clinic in 2020. Examination revealed scaly plaques, fissures, and lichenification on the palmar surfaces bilaterally, and indurated pink papules and plaques on the feet bilaterally. A shave biopsy of the left upper extremity and a 4 mm punch biopsy of the right lower extremity were performed at this time. Histopathological analysis revealed an atypical lymphocytic perivascular infiltrate with epidermotropism. Immunohistochemistry was positive for CD3, with a CD4:CD8 ratio favoring CD4, and a reduction in CD7 expression. The patient's lesion was diagnosed as MFPP. Unfortunately, the patient was lost to follow-up but reappeared in 2023 with the persistence of intensely pruritic plaques on her bilateral palms (Figure 1) as well as her left big toe. Physical exam was notable for hyperkeratotic plaques on the left palm, left third metacarpophalangeal joint, right 3rd proximal interphalangeal, and right thumb metacarpophalangeal joint. Due to its rarity, the management of MFPP followed literature recommendations.1 A referral to oncology was reiterated for a comprehensive evaluation.
