Sustained remission of metastatic Merkel cell carcinoma with treatment of HIV infection

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer of presumed neuroendocrine origin. ¹ The prognosis for metastatic MCC is typically very poor, despite treatment.²

CASE HISTORY

The patient, now aged 52, was found to be HIV-positive 14 years ago after an episode of multi-dermatomal herpes zoster. He declined antiretroviral therapy. 10 years later a cystic lesion appeared on one buttock. His viral load was then >750 000 copies/mL and CD4 count was 267 cells/mL. A few months later a large mass was excised and was found to be MCC of the skin and subcuits with the classic trabecular features. The inguinal lymph nodes likewise showed trabecular MCC, and a CT scan revealed deep pelvic nodal involvement. The patient declined chemotherapy but had seven out of a prescribed thirty rounds of radiation for the nodal disease. Subsequently he developed a cough with dyspnoea and, five months after the original biopsy, chest X-ray and a CT scan were consistent with multiple pulmonary metastases. The patient declined chemotherapy or further radiation therapy, but he did elect to begin highly active antiretroviral therapy (HAART) with twice daily stavudine 40 mg, lamivudine 150 mg, and ritonavir 200 mg and subcutaneous interleukin-2 (IL-2) 22×10⁶ units five days each month. Viral load quickly decreased to below 50 copies/mL and the CD4 cell count rose to 676 cells/mL. The dyspnoea and cough resolved, as did the inguinal adenopathy. Repeat chest CT scans after five and eleven months of HAART plus IL-2 showed resolution of the pulmonary disease. The patient now feels well, his weight is normal, and there are no obvious signs of MCC. His viral load is at present undetectable.

COMMENT

HIV positive individuals have a relative risk for MCC of 13.4.³ MCC also seems to occur in excess among patients receiving immunosuppressive treatment after organ transplantation⁴ and in those with other cancers.⁵ In the immunocompetent host, potentially malignant clones are probably held in check by the immune system—most likely T cells. In our patient immune reconstitution with HAART along with IL-2 to make ‘new’ T cells may have helped to overcome the metastatic MCC. Since current treatments for this disease are rather ineffective,² trials of IL-2 (and HAART in HIV-positive patients) may be warranted.