Abstract:

We present here the case of a 60-year-old woman in whom Chronic Lymphocytic Leukemia (CLL) was found incidentally after a new diagnosis of Mycosis Fungoides (MF). MF was first considered after histopathology showed a lichenoid tissue reaction consisting of a dense band-like lymphocytic infiltrate with focal areas of epidermotropism in the upper dermis, and a few extravasated erythrocytes. Immunohistochemical studies for CD3 (T-cells) and CD20 (B-cells) demonstrated a CD3-predominant infiltrate. Lab work showed lymphocytosis on CBC. This was followed by flow cytometry, which demonstrated CD5+, CD23+ lambda light-chain restricted B-cell population, and CLL was subsequently diagnosed. This case highlights two important points: (1) the variant of purpuric MF which can clinically and histopathologically mimic pigmented purpuric dermatosis (PPD) and (2) the need to consider additional awareness and testing for other lymphoproliferative diseases in patients diagnosed with MF. MF has numerous clinical variants, and their histopathologies can mimic other inflammatory skin conditions such as psoriasis, atopic dermatitis, ichthyosis, and PPD. This case features the pigmented purpuric variant, a rarer form of MF that can be difficult to distinguish from PPD, and often requires additional histopathologic evaluation. About 40% of monoclonal PPD has clinical and pathologic features of MF, including lymphocytes aligned along the epidermal side of the dermoepidermal junction. Our case also emphasizes the importance of working up patients with MF for underlying malignancy. Patients who develop primary MF are at an increased risk of developing visceral and hematologic malignancies. Concomitant diagnosis of MF with CLL has been reported previously; basic laboratory screening for malignancy in MF patients may lead to earlier diagnosis. Earlier detection could help better understand prognosis and improve patient management and overall survival.

Financial Disclosure:
No current or relevant financial relationships exist.

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Marisa Riley, BS