Case Report
A 60-year-old man with a history of Hodgkin lymphoma that had been treated with chemotherapy 6 years prior presented to our dermatology clinic with a persistent pruritic rash on the back, abdomen, and bilateral arms and legs. The eruption initially began as localized discrete lesions on the lower back 1 year prior to the current presentation; at that time a diagnosis of psoriasis was made at an outside dermatology clinic, and treatment with mometasone furoate cream was initiated. Despite the patient’s compliance with this treatment, the lesions did not resolve and began spreading to the arms, legs, chest, and abdomen. His current medications included lisinopril, escitalopram, aspirin, and omeprazole.
On presentation to our clinic, physical examination revealed round, scaly, pink plaques and tumors of variable sizes (3–10 cm) distributed asymmetrically on the chest, back, abdomen, arms, and legs (Figure 1). The lesions were grouped in well-defined areas encompassing approximately 30% of the body surface area. No lymphadenopathy was appreciated. In vivo reflectance confocal microscopy (RCM) performed on one of the lesions revealed disarray of the epidermis with small, weakly refractile, round to oval cells scattered within the spinous layer and dermoepidermal junction (Figure 2). Additionally, these weakly refractile, round to oval cells also were seen in vesiclelike dark spaces, and hyporefractile basal cells were appreciated surrounding the dermal papillae. Mycosis fungoides (MF) was diagnosed following correlation of the RCM findings with the clinical picture.
Figure 1. Mycosis fungoides with round, scaly, pink plaques of variable sizes ranging from 3 to 10 cm distributed asymmetrically on the back, flank, and arms (A and B).
Figure 2. Reflectance confocal microscopy of the stratum spinosum revealed epidermal disarray with small, weakly refractile, round to oval cells (blue markings) scattered among keratinocytes in vesiclelike dark spaces (A). At the level of the dermoepidermal junction, there were more weakly refractile, dermal, papillary rings compared to normal skin, as well as more weakly refractile, round to oval cells in the epidermis and dermis (B).
A biopsy was performed, with pathologic examination confirming the diagnosis of tumor-stage MF. Parakeratosis with epidermotropism of lymphocytes was noted along the basal layer and into the spinous layer of the epidermis (Figure 3). Underlying the epidermis there was a dense mononuclear infiltrate and conspicuous eosinophils extending to the deeper reticular dermis. The infiltrating cells had cerebriform nuclei and large pale cytoplasm. On immunostaining, the lymphocytes were positive for CD3 and CD4, and negative for CD5, CD7, and CD8. The patient was referred to the oncology department for disease management. Staging workup including computed tomography, flow cytometry, and T-cell receptor gene rearrangement were consistent with tumor-stage MF (T3N0M0B0).
Figure 3. Atypical enlarged lymphocytes in the epidermis with hyperchromatic irregular nuclei of cells (inset) as well as a dense infiltrate in the dermis (A)(H&E, original magnifications ×10 and ×50 [inset]). CD4 immunohistochemical staining revealed atypical lymphocytes with dermal and epidermal infiltration (B)(original magnification ×10).