Challenging differential diagnosis, Rare disease
Ian Beiser, Joon Yim, Erin Robles-Sherman, Gene S. Mirkin, Xingpei Hao
Department of Podiatry, Foot and Ankle Specialists of The Mid-Atlantic, LLC, Rockville, MD, USA
Am J Case Rep 2020; 21:e923361
Available online: 2020-08-13
Mycosis fungoides palmaris et plantaris (MFPP) is a rare variant of the cutaneous T cell lymphoma mycosis fungoides (MF). Here we report the case of a middle-aged man with MF on the sole of his left foot.
CASE REPORT: A 54-year-old man had a diffuse, hard lesion in the middle of the arch on the sole of his left foot for 3 years. Physical examination revealed a 3-cm scaly, keratotic patch with slight erythema on the left plantar central arch. Histopathological evaluation of a punch biopsy specimen revealed infiltration of atypical lymphocytes in the upper dermis. Immunostaining of the atypical lymphocytes showed strong expression of CD3, CD4, and CD5; reduced expression of CD7 and CD8; and no expression of CD20. Periodic acid-Schiff staining was negative for fungi. The patient’s lesion was diagnosed as MFPP and he was treated with topical psoralen plus ultraviolet A (PUVA) photochemotherapy. At 5-year follow-up, his condition was in complete remission.
CONCLUSIONS: MFPP is a rare clinical variant of MF restricted to the palmoplantar area, and is histologically characterized by upper dermal infiltration of atypical lymphocytes with preserved CD3, CD4, and CD5 expression but decreased CD7 and CD8 expression. PUVA photochemotherapy is a treatment option associated with excellent prognosis.
Keywords: Foot Diseases, Lymphoma, T-Cell, Cutaneous, Mycosis Fungoides, PUVA Therapy