Polydactylous Longitudinal Melanonychia Acquired following Total Skin Electron Beam Radiation Therapy for Sézary Syndrome

weeks later, examination of all 20 nails revealed longitudinal pigmentation in 13 of 20 nail units with bands of different widths ranging from 2 to 10 mm. There was no pigmentation on the nail folds ( fig. 1 ). Given the polydactylous multiple nail involvement and the recent onset of these findings, we recommended baseline photographs and close monthly monitoring. We find this unique observation of acquired polydactylous LM as a side effect of TSEBT important for physicians to understand. There is a single report of 3 cases of transverse melanonychia on multiple fingernails following TSEBT for mycosis fungoides (1 African-American, 2 Caucasian) where the pigmentation was displaced outwards as the nails grew [2] . However, this is the first case of LM seen after TSEBT for cutaneous T-cell lymphoma (CTCL). To the Editor, Longitudinal melanonychia (LM), the presence of longitudinally oriented pigmented band(s) along the nail unit, can occur in a single or multiple nail units, and is most commonly seen in individuals with skin phototypes 4–6 [1] . We would like to call to your attention the case of a 60-year-old Caucasian woman with no prior abnormalities of the nails, who presented with a 2-year history of progressive generalized erythema and keratoderma of her palms and soles. She had been seen by multiple physicians who diagnosed her has having a photosensitivity reaction. Discontinuation of her hydrochlorothiazide and treatment with low-dose prednisone did not result in any significant improvement. Subsequently, a skin biopsy revealed lymphocytic atypia with a skewed CD4:CD8 ratio, and PCR-based T-cell receptor gene rearrangement studies showed matching T-cell receptor clones in the skin and blood. Flow cytometry of her peripheral blood showed an aberrant CD3+/ CD4+CD26– lymphocyte population (absolute count of 2,600 cells/μl). These findings supported a diagnosis of Sézary syndrome. The patient was initially treated with bexarotene at a daily dose of ∼ 200 mg/m 2 in conjunction with 100 μg of interferon gamma 3 times a week, daily applications of mechloretamine 0.01% in petrolatum, clobetasol 0.05% ointment for her palms and soles, and extracorporeal photopheresis for 2 consecutive days every 4 weeks. Six months after starting this regimen, the patient continued to have erythroderma and significant blood involvement on flow cytometry. Therefore, the decision to add total skin electron beam radiation therapy (TSEBT) to her regimen was made. The patient received 40 Gy worth of radiation to her body and an additional 10 Gy to her feet. During the 20 weeks of radiation treatment, the patient continued with her multimodality immunotherapy. One month after completing TSEBT, 85% of her skin had cleared and her Sézary count on flow cytometry dropped to 150 cells/μl. Secondary to the radiation therapy, the patient lost all of her scalp and body hair and all of her fingernails and toenails. Two months after the completion of TSEBT, her nails started to grow back. Notably, a discrete 4-mm longitudinal brown streak was appreciated on the nail unit of her right second finger. Two Received: March 17, 2015 Accepted: April 8, 2015 Published online: June 3, 2015