A Case of Malignant Melanoma with In-Transit Metastasis That Responded to Intravenous Infusion of Interferon-β
The patient was a 77-year-old male with rash on the fifth toe of the left foot and lower left leg. His medical history included hypertension, diabetes, and malignant melanoma that was surgically removed (fifth toe amputation) at our department 14 years ago (fig. ). Otherwise, his family history was unremarkable. Three months before presentation, a skin ulcer appeared at the same site, and red nodules developed on the lower left leg. Subsequently, the patient consulted the Kariya Toyota General Hospital. Malignant melanoma was suspected, and the patient was referred to our department.\nAt the amputation site on the left foot, there was a skin ulcer measuring 25 × 20 mm with several red nodules, primarily on the anterior surface of the lower left leg (fig. ). Skin biopsies were obtained from the red nodules on the lower leg and the skin ulcer on the left foot.\nHistopathological examination of both lesion samples revealed tumor cells with eosinophilic cytoplasm and medium-to-large nuclei with distinct nucleoli extending through all layers of the dermis and into some fatty tissue. The tumor comprised an alveolar structure and had a solid proliferative area (fig. ). Immunostaining was positive for vimentin, S-100, HMB-45, melanoma, and Melan-A. The MIB-1 index was 38.3%. Based on these results, a diagnosis of recurrent malignant melanoma with in-transit metastasis was made.\nSubtotal integumentectomy was scheduled; however, 2 weeks later, the patient developed acute myocardial infarction and was hospitalized at Kariya Toyota General Hospital. Treatment for acute myocardial infarction continued for 1 month; thereafter, the patient was transferred to our department. As the myocardial infarction decreased the patient's tolerance to surgery, intravenous infusion of IFN-β was decided as the treatment of choice. Initially, IFN-β was administered at 3 million U/day for 10 consecutive days. As a countermeasure against fever, which is a side effect of IFN-β, Loxonin® was orally administered three times per day on the days of infusion. Thereafter, the patient was treated as an outpatient, with intravenous infusion of IFN-β 3 million U/day once a week. Twenty-six weeks later, the skin ulcer on the fifth toe of the left foot was cured, the nodes on the left leg had disappeared, and only pigmentation was observed (fig. ). After 1 year, the regimen was changed to intravenous infusion of IFN-β 3 million U/day once every 2 weeks. The patient's progress has been satisfactory, with no evidence of recurrence or metastasis at 1 year and 9 months after treatment (fig. ). The patient continues to receive IFN-β 3 million U/day every 2 weeks.