Late-Onset Bexarotene-Induced CD4 Lymphopenia in a Cutaneous T-cell Lymphoma Patient

The patient was subsequently started on acitretin, topical corticosteroids, and hydroxyzine. However, the erythroderma progressed and he developed fever, chills, and malaise, and he was hospitalized 2 months later for intensive therapy and to rule out infection. He improved on daily wet wraps, topical steroids, oral antibiotics, and initiation of narrowband UVB therapy. He was discharged 1 week later. Acitretin was switched to bexarotene 3 months later due to peeling and cracking of the palmoplantar skin. The initial dose was 225 mg once daily, which was steadily increased over the next 4 months to a therapeutic dose of 600 mg once daily, which was much lower than the maximum dose of 400 mg/m² daily (calculated at 750 mg/d in our patient). The patient achieved clinical remission 1 year after initiation of bexarotene in conjunction with narrowband UVB therapy. Serum eosinophils also normalized. Because there were no intolerable side effects, this dose was continued for 2 more years before it was slowly tapered to 375 mg once daily over a 1-year period. The new dose was maintained thereafter. Secondary hypertriglyceridemia and hypothyroidism, known side effects of bexarotene, developed 1 and 5 months after initiating therapy, respectively, and were treated with levothyroxine and fenofibrate. Blood counts were checked every 3 months and remained within reference range. Within the first few months of therapy, lymphocytes did trend down to 16.8%, but segmented neutrophils were normal at 59.4%. For the next 5 years the total WBC count and differential remained within reference range. T-cell subsets and flow cytometry data were not measured. No new medications were started during this period, and none of his existing medications had lymphopenia as a known side effect.

Five years after the initial diagnosis, the patient was still on bexarotene and was suspected to have pneumonia that was treated by his primary care provider with cefuroxime and azithromycin for 2 weeks with no improvement. He was then admitted to the hospital with shortness of breath, productive cough, night sweats, and dyspnea of 1 month’s duration. There was no associated weight loss or fever. Notably, the skin was clear. He was further treated for community-acquired pneumonia, first with vancomycin and ceftazidime, then with ciprofloxacin and sulfamethoxazole-trimethoprim, with no improvement. A CBC with differential was obtained on the patient’s first admission and revealed a WBC count of 3600/µL with decreased lymphocytes (8.6%), no eosinophilia, and anemia (hemoglobin, 10.5 g/dL [reference range, 33–37 g/dL]). T-cell subset studies revealed a CD4:CD8 ratio of 0.06 to 1 (absolute CD4⁺ cells, 6/µL; absolute CD8⁺ cells, 107/µL). The patient also had an elevated lactate dehydrogenase level of 1015 U/L (reference range, 100–200 U/L) and a normal comprehensive metabolic panel. A comprehensive workup, including urine and blood cultures, serum Cryptococcus and coccidioidomycosis IgG/IgM, histoplasmosis urine antigen, legionella, HIV, purified protein derivative (tuberculin), and aspergillosis galactomannan antigen panel, was negative. Blood tests for HIV and human T-lymphotropic virus also were negative. Bronchoscopy with cytology and sputum cultures for fungi, acid-fast bacteria, and viruses identified Pneumocystis jiroveci in the bronchial wash. Pneumocystis pneumonia was treated with intravenous clindamycin, primaquine, and leucovorin. The patient’s WBC count continued to drop over the next 2 weeks to a nadir of 1.7% with few lymphocytes noted on the differential. At that point, the bexarotene was stopped and was considered causative in inducing CD4 lymphopenia, resulting in opportunistic infection. The patient steadily improved and was discharged on sulfamethoxazole-trimethoprim prophylaxis for pneumocystis after a 4-month hospitalization.

His CD4 count slowly improved over the next 18 months; however, his skin disease recurred and progressed to exfoliative erythroderma with marked scarring alopecia (Figure 3), facial swelling, extreme pruritus, and notable eosinophilia. Repeat computed tomography was negative for extracutaneous involvement. A repeat skin biopsy showed recurrent mycosis fungoides similar to the original biopsy (Figure 4). Topical steroids and narrowband UVB therapy were restarted. A bone marrow biopsy revealed no definitive lymphoma, but the peripheral blood showed occasional CD8⁺ “flower cells” and no CD4⁺ Sézary cells. Two repeat molecular studies failed to show the T-cell receptor gene rearrangement. Localized electron beam radiation therapy, lenalidomide, and clobetasol were tried without benefit. The patient was hospitalized 3 months later and was started on wet wraps as well as weekly infusions of the histone deacetylase inhibitor romidepsin (14 mg/m² over a 4-hour period) on days 1, 8, and 15 of a 28-day cycle with rapid improvement. He experienced transient slight neutropenia with the first several treatments that quickly resolved. His skin was clear while on a regimen of triamcinolone, wet wraps, and intravenous romidepsin. He demonstrated visible improvement after 3 weekly infusions of romedepsin (Figure 5). His skin disease cleared after 9 infusions of romidepsin, and he currently remains in remission; however, he developed presumed bronchopneumonia after approximately 3 to 4 infusions. He then presented with severe headaches after his ninth infusion and was found to have cryptococcal meningitis. Romedepsin was stopped and he was treated with systemic antifungal therapy. His CTCL never recurred despite not restarting romidepsin.

Figure 3. Mycosis fungoides relapsed 1.5 years after hospitalization for Pneumocystis jiroveci pneumonia (6.5 years after the initial diagnosis) with facial edema, exfoliative erythroderma, and scarring alopecia on the scalp.

Figure 4. A repeat skin biopsy following recurrent disease showed spongiotic and lichenoid infiltrate with folliculotropism consistent with relapsed mycosis fungoides (H&E, original magnification ×4).

Figure 5. The scalp was clear of disease after 3 cycles of intravenous romidepsin, topical triamcinolone, and wet wraps.