A Man With a Rash on Nearly Half of His Body for 8 Years

Richard Harold Flowers IV, MD; Stephany Lynn Vittitow, BA; Corina Rusu, MD, PGYIII


August 25, 2020


A diagnosis of mycosis fungoides (MF) was made on the basis of the patient's history, physical examination results, and biopsy findings. The biopsy results revealed compact hyperkeratosis of the stratum corneum, epidermal lymphocytes, and exocytosis, with collections of atypical lymphocytes forming Pautrier microabscesses scattered throughout the epidermis (Figure 2).

Figure 2.

The lymphocytes showed hyperchromasia and perinuclear halos. Histologic examination also revealed papillary dermal fibrosis and superficial perivascular lymphocytes localized mostly above the blood vessels. The atypical lymphocytes scattered in the dermis and epidermis were CD3 positive (Figure 3), and the CD4 to CD8 ratio was 20:1 (elevated). Immunohistochemistry analysis showed greater than 60% loss of CD5 and greater than 60% loss of CD7. Flow cytometric analysis of serum revealed no atypical T-cell population.

Figure 3.

The results of basic laboratory studies, including a complete blood cell count, comprehensive metabolic panel, and measurement of serum lactate dehydrogenase level, were unremarkable aside from a mild normocytic anemia. A chest radiograph displayed no hilar lymphadenopathy. These findings were consistent with a diagnosis of classic MF in a generalized patch/plaque stage (involving > 10% of body surface area), which correlates with stage IB disease (see below for more detail on staging).

Cutaneous T-cell lymphomas are a heterogeneous group of monoclonal T-cell proliferations that primarily involve the skin, of which MF is the most common. MF is likely secondary to a stepwise accumulation of mutations in the setting of chronic antigenic stimulation, resulting in uncontrolled clonal memory helper T-cell expansion and accumulation in the skin.[1]

MF most commonly occurs in patients older than 60 years and generally has an indolent, progressive course over years or decades.[2] Classic progression is from patches to thin plaques, then to thicker plaques and tumors. The latter rarely spread to regional or distant lymph nodes, bone marrow, and other organs.[2]

The characteristic skin lesions of MF are well-defined, flat to slightly indurated patches and plaques, and they often have prominent variability in size, shape, and color. The mildly pruritic lesions may be round to oval or horseshoe in shape with an overlying wrinkly scale.[2] The distribution favors non–sun-exposed or "double-covered" areas, including the breasts, buttocks, lower trunk, and groin.

Poikiloderma—characterized by hyperpigmentation, hypopigmentation, atrophy, and telangiectasia—develops in long-standing lesions. Tumors of later-stage disease tend to ulcerate, and superinfection is common.[2] Approximately 90% of patients with early MF have disease that does not progress to the tumor stage and do not exhibit extracutaneous signs of the disease in their lifetime.[3]


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