Pagetoid Reticulosis presenting as a single small scaly plaque on the foot

    Clinical findings. The patient is a 24-year-old woman with 10.0 × 10.0 mm dermal plaque on her right medial dorsum of foot, which was noticed for the first time 7 months ago. The lesion started as a small red spot that was slowly increasing in size. The patient is otherwise healthy without significant medical history. The lesion is a small round dermal plaque with scaling in the center and raised sharply demarcated, red peripheral borders. The clinical differential diagnosis included dermatofibroma, porokeratosis, or granuloma annulare. A skin punch biopsy of the border of the lesion was taken.

     

    Pathologic findings. Histologic sections showed a psoriasiform epidermis with acanthosis and hyperkeratosis associated with a dense epidermotropic atypical lymphoid infiltrate located predominantly in the basal layer with a pagetoid pattern. The atypical lymphoid cells were small to intermediate in size with irregular nuclear contours, hyperchromatic nuclei, some with distinct nucleoli, and some with a perinuclear halo. Rare mitotic figures were also observed. The superficial dermis contained a mild perivascular lymphohistiocytic infiltrate with rare atypical-appearing cells. Immunohistochemical studies revealed that the neoplastic cells were positive for CD3and CD8 and were negative for CD4 and CD7. Reactive T-cells positive for CD4 and rare B-cells positive for CD20 were observed in the upper dermis.

     

    Molecular findings.  TCR-γ gene rearrangements could not be verified by PCR due to the technical failure.

     

    Staging, treatment, and follow-up. She was diagnosed with pagetoid reticulosis. Patient received a complete, conservative reexcision of the residual lesion. She is disease-free for 33 months.

     

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