The present case provides direct evidence of human herpesvirus 6 reactivation in resected lymph node tissue in a patient with drug-induced hypersensitivity syndrome. This case clearly demonstrates that appropriate pathological evaluation of lymphadenopathy for drug-induced hypersensitivity syndrome, which mimics malignant lymphoma in clinical, radiological, and pathological findings, is required.
CASE REPORTA 57-year-old woman was referred to our department because of generalized erythema involving mainly her face and upper trunk, with a morbilliform eruption for a week, persistent pyrexia, and a sore throat for the preceding 3 weeks. She had been treated for bipolar disorder and had a history of atopic dermatitis and bronchial asthma in her childhood. She had been on lorazepam, famotidine, and loxoprofen for a decade, and carbamazepine had been started 1 month prior to coming to our department ( Fig. 1, day 1). She was allergic to soybeans, corn, eggs, and rice. She had not been in contact with any sick persons. At her first visit to our department (day 34), physical examination showed mild periorbital edema and expanding erythema from her face to both lower legs, with a morbilliform eruption, but no mucosal ulcers or erosions were noted. Thus, she was tentatively diagnosed as having an adverse cutaneous reaction to carbamazepine; therefore, carbamazepine was stopped, and oral prednisolone therapy was started at a dose of 20 mg/day. One week after starting the prednisolone therapy (Fig. 1, day 43), her sore throat and high-grade fever had almost disappeared, and some aspects of the cutaneous lesions, such as pigment deposition and nonpalpable purpura, had improved. Of note, at this time, she noticed generalized lymphadenopathy and returned to our department.At her 2nd visit to our department (day 43), physical examination showed generalized superficial lymphadenopathy (supraclavicular, cervical, axillary, and inguinal), and each node was 20 mm in size, firm, nonfixed, circumscribed, and rubbery, suggesting lymphoma. Laboratory examination revealed marked elevations of her white blood cell count (37,400/l, with 1% basophils, 7% eosinophils, 25% neutrophils, 44% lymphocytes, 14% atypical lymphocytes, and 3% monocytes), lactate dehydrogenase (1,657 IU/liter), and soluble interleukin 2 receptor (11,600 U/ml). Moderate elevations of serum hepatic biliary enzymes were also noted (aspartate aminotransferase, 81 IU/liter; alanine aminotransferase, 144 IU/liter; alkaline phosphatase, 264 IU/liter; ␥-glutamyl transpeptidase, 371 IU/liter). Two sets of blood cultures were negative, and no evidence of a recent infectious mononucleosis (IM) syndrome (Epstein-Barr virus) or IM-like syndrome (cytomegalovirus, Toxoplasma gondii, human immunodeficiency virus) was detected (Fig.
