LAUSR

Pediculosis and phthiriasis are infestations with lice, a common ectoparasite that has been reported in all countries and throughout all socioeconomic demographics. The prognosis of louse infestation is typically very favorable; however, psychosocial stress and stigma may be prominent, and complications including secondary staphylococcal infections from scratching and blepharoconjunctivitis from eyelash involvement have been reported. Rarely, severe iron deficiency anemia secondary to louse infestation may occur, presumably because of chronic low-level blood loss from parasitic feeding. Additionally, body lice serve as a vector for other infectious entities including typhus and trench fever. Lice have limited mobility, and transmission is by contact. Pubic lice specifically are transmitted either through sexual activity or through fomites such as bedding or clothing. Additionally, pubic lice have been postulated as a surrogate marker for sexually transmitted infections in general, suggesting that appropriate testing for other venereal diseases should be offered to patients with pubic lice. Diagnosis of pubic lice involves visual identification of the organisms, such as with dermoscopy, light microscopy, or other such investigation. Skin biopsy is not required and is rarely performed, as histopathologic findings are typically non-specific. The following case describes a rare and unique histopathologic finding of pubic lice infestation. A 64-year-old male presented to a dermatology outpatient clinic for a new pruritic eruption of 1-month duration. The rash had started on the upper legs and then spread to involve the back, abdomen, buttocks, and groin. He had been previously treated unsuccessfully with a 10-day course of doxycycline, cetirizine, topical clotrimazole/ betamethasone combination, and triamcinolone. Physical examination revealed pin-point brown to pink scaly papules of the upper legs, buttocks, groins, abdomen, and umbilicus. A biopsy specimen from the abdomen showed a non-specific sparse perivascular inflammatory infiltrate but also revealed an ovoid eosinophilic structure closely adherent to and surrounding a hair shaft (Figure 1). The clinical images were reviewed in conjunction with histopathologic examination, at which time the brown lesions were noticed to display a triangular silhouette suspicious for crab lice. This suspicion was communicated to the clinician, who subsequently collected umbilical hairs from the patient at follow-up. Upon examination with light microscopy, crab lice were observed as well as nits adherent to hair shafts via the nit sheath (Figure 2). Pubic lice are typically found in the anogenital area as the name would imply; however, as in this case, more distant anatomic sites, such as the scalp and body hair, have been reported. Skin biopsy is typically not required for the diagnosis of louse infestation, and the histopathologic findings are mostly non-specific, showing a typical arthropod assault response with a wedge-shaped infiltrate of lymphocytes and eosinophils as well as dermal hemorrhage. A recentlyreported case describes a patient with biopsy-confirmed transient acantholytic dyskeratosis (Grover disease) who failed standard treatment and experienced improvement in his pruritic symptoms only upon discovery and appropriate treatment of a concomitant pubic lice infestation. This could suggest louse infestation as a possible trigger or exacerbating factor for Grover disease.