Primary varicella-zoster virus (VZV) infection usually occurs in childhood and in the majority of cases runs a self-limiting course. In infants, adults, and immunocompromised individuals, however, the infection can be serious if certain complications develop.

We report the case of an immunocompetent adult patient with VZV infection complicated by rhabdomyolysis.

The patient was a 29-year-old man, with no relevant past medical history, who presented at the emergency department with pruritic skin lesions. He said that the lesions, which were not initially filled with fluid, had erupted in successive crops over the previous 24hours, causing intense itching. He also reported fever of 39°C, a lack of strength and energy, and loss of appetite. He had experienced general malaise for a week and had also had low-grade fever and muscle pain. Physical examination revealed a rash, mainly affecting the trunk, consisting of fluid-filled vesicles at different stages of development on a red base; there were no vesicles on the mucous membranes or on the palms or soles. Blood tests revealed elevated values for creatine phosphokinase (11480 U/L), aspartate aminotransferase (165 U/L), alanine transaminase (63 U/L), lactate dehydrogenase (820 U/L), and myoglobin (200.1ng/mL). The other values were within normal ranges and included pH, 7.38; bicarbonate, 24 mEq/L; creatinine, 0.98mg/dL; urea, 29mg/dL; sodium, 139mmol/L; potassium, 4.1mmol/L; and chloride, 100mmol/L. No abnormalities were observed on the chest radiograph. A Tzanck smear revealed the presence of multinucleated giant cells and acantholytic keratinocytes. A diagnosis of varicella complicated by rhabdomyolysis was established and the patient was admitted for treatment with acyclovir and intravenous fluid therapy with normal saline. Additional measures, such as the administration of mannitol, furosemide, or bicarbonate, were not required. During the patient's stay in hospital, human immunodeficiency virus (HIV) infection was ruled out and there was no impairment of renal function. The skin lesions and blood results improved gradually, and the patient was discharged after a week, having developed no other complications.

The most common complications of VZV infection are bacterial superinfection, laryngitis, and pneumonia. Nervous system complications include encephalitis and cerebellitis and, very rarely, polyneuritis, myelitis, radiculitis, and optic neuritis. Hepatitis and myocarditis have also been described. Rhabdomyolysis is a rare complication of primary VZV infection, with only few cases reported in the literature.1–8 In otherwise healthy patients with varicella, morbidity and mortality due to rhabdomyolysis are 10 to 20 times higher in adults than in children.2

Rhabdomyolysis is characterized by massive tissue breakdown leading to the passage of toxic intracellular metabolites into the circulatory system. This can cause acute kidney failure, hyperkalemia, metabolic acidosis, and disseminated intravascular coagulation. Possible causes of rhabdomyolysis include epileptic seizures, drugs such as statins, alcohol intake, trauma, strenuous physical exercise, and, more rarely, infections. The only risk factor in our patient was VZV infection. The most common viral causes of rhabdomyolysis are influenza, HIV, and enterovirus infection.9 Influenza appears to be the viral infection most commonly associated with renal impairment in patients with rhabdomyolysis.10 The risk of renal impairment in patients with rhabdomyolysis secondary to VZV infection does not appear to be related to creatine phosphokinase levels.5

Although rhabdomyolysis due to primary VZV infection is believed to be rare, it might be underdiagnosed. Because creatine phosphokinase levels are not routinely measured in patients with varicella, mild to moderate cases of rhabdomyolysis could go unnoticed5 in the absence of suggestive signs or symptoms such as abnormal urine color, weakness, or intense muscle pain, as was the case with our patient.

In conclusion, rhabdomyolysis should be considered as a possible complication in patients with primary VZV infection as this will help to ensure prompt initiation of appropriate treatment to prevent potentially serious complications.