Bugs and Blood Cells

Roesch et al examine the case of a 63-year-old Hispanic man who was admitted to the hospital for altered mental status when he presented to the nephrology clinic for a follow-up visit for chronic renal insufficiency. He had been presumptively diagnosed with allergic interstitial nephritis based upon ongoing renal insufficiency with concurrent eosinophilia and eosinophiluria, but he had not had a renal biopsy because steroid bursts resulted in clinical improvement. Pathologic analysis of the patient's skin biopsy did not confirm the suspected lymphoma. Instead, it revealed vesiculating epidermal spongiotic dermatitis with superficial perivascular lymphoeosinophilic infiltrate. Hematoxylin and eosin staining demonstrated arthropod fragments within the inflammatory crust of serum and eosinophils, establishing a pathologic diagnosis of Sarcoptes scabiei infection, also known as scabies. The patient was treated with 2 doses of oral ivermectin (0.2 mg/kg) administered 2 weeks apart. This treatment was augmented with permethrin and clobetasol cream. He reported an immediate decrease in pruritus, and his eosinophil count fell simultaneously and abruptly to within normal limits.