Although human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus, it seems to induce a precancerous state that can lead to adult T-cell leukemia–lymphoma (a subtype of cutaneous T-cell lymphoma), instead of being directly carcinogenic. HTLV-1 is associated with a long latency period, and most affected patients are exposed to the virus early in life. The four clinical variants of adult T-cell leukemia–lymphoma — acute, lymphomatous, chronic, and smoldering — affect the clinical presentation and prognosis.
A 65-year-old man with end-stage renal disease and a history of syphilis presented with a leg injury and a diffuse pruritic rash. A recent serologic test had been positive for human T-lymphotropic virus type 1. A diagnostic procedure was performed. A new Case Record of the Massachusetts General Hospital summarizes.
• What are some general features of cutaneous T-cell lymphoma?
Cutaneous T-cell lymphoma can be manifested by pruritic scaly plaques and papules that usually occur on the buttocks and other nonphotodistributed areas and appear gradually. There are many types of cutaneous T-cell lymphoma. Mycosis fungoides accounts for the majority of cases of T-cell lymphoma with cutaneous involvement (approximately 65%), whereas adult T-cell leukemia–lymphoma accounts for less than 1% of cases. Mycosis fungoides can be manifested by a patch, plaque, or tumor and may also progress to involve the lymph nodes and viscera.
• HTLV-1–associated adult T-cell lymphoma–leukemia occurs most commonly in patients living in what geographic regions?
HTLV-1–associated adult T-cell leukemia–lymphoma occurs most frequently in patients who live in areas where HTLV-1 is endemic, such as the Caribbean basin, southwestern Japan, and parts of South American and central Africa, but it can also be identified in the United States.
Figure 1. Clinical Photographs.
Figure 2. Skin-Biopsy Specimen (Hematoxylin and Eosin).
Morning Report Questions
Q: Is adult T-cell leukemia–lymphoma difficult to distinguish from mycosis fungoides?
A: The diagnosis of adult T-cell leukemia–lymphoma with cutaneous involvement is challenging because it mimics other forms of T-cell lymphoma with cutaneous involvement, particularly mycosis fungoides. Skin biopsies from patients with adult T-cell leukemia–lymphoma often initially lead to a diagnosis of mycosis fungoides. Findings that suggest that cutaneous patches or plaques are caused by adult T-cell leukemia–lymphoma instead of mycosis fungoides include increased expression of CD25 and distribution of the patches or plaques in photodistributed areas. Among patients who live in areas where HTLV-1 is endemic, serologic testing for HTLV-1 may be positive both in those with adult T-cell leukemia–lymphoma and in those with mycosis fungoides. Thus, in a patient who has HTLV-1 infection, the accurate diagnosis of adult T-cell leukemia–lymphoma requires evidence of proviral DNA integration, obtained by means of direct polymerase-chain-reaction testing of skin lesions.
Figure 3. Skin-Biopsy Specimen (Immunoperoxidase).
Q: What is the prognostic implication of cutaneous involvement in adult T-cell leukemia–lymphoma?
A: Approximately 50% of patients with adult T-cell leukemia–lymphoma have some form of cutaneous involvement, such as patches, plaques, papules, nodules, tumors, erythroderma, or purpura. The type of skin lesion is of prognostic importance, since the survival rate is lower among patients with erythroderma or tumors than among patients with only patches or plaques. Among patients with acute or lymphomatous adult T-cell leukemia–lymphoma, cutaneous involvement has been associated with a decreased survival rate.