CASE
An 84-year-old white male was referred to a teaching hospital dermatology clinic in the southern United States for evaluation of a diffuse erythematous eruption that had been present for 2 years. The eruption was resistant to topical corticosteroids. The condition was asymptomatic despite its widespread nature, but it covered his arms, trunk, and lower extremities (see Figure 1). The eruption was largely confluent; however, there were multiple small nummular patches present. The patient denied any history suggestive of a contact dermatitis or drug eruption, though he was taking multiple medications. Family members reported no similar skin findings.
Histologic examination of a 4-mm punch biopsy specimen revealed a superficial and mid-perivascular infiltrate dominated by lymphocytes without spongiosis (see Figure 2) Solar elastosis was found to be present in the dermis, and there was no evidence of vasculitis. Immunohistochemistry studies were performed, and results proved to be consistent with a nonspecific reactive process.
At follow-up 1 month after the initial biopsy, the patient complained of numbness in both arms with no other associated neurologic complaints. The previous biopsy specimen was subjected to an acid-fast Fite stain (see Figure 3). The supplementary pathology report described acid-fast bacilli in foamy histiocytes, the perivascular infiltrate, and the nerves.
Does this patient have tinea corporis, a drug eruption, subacute cutaneous lupus erythematosus (SCLE), or leprosy?
DISCUSSION
Tinea corporis is a cutaneous fungal infection of the neck, trunk, arms, and/or legs. The typical clinical presentation is that of a scaling, well-circumscribed, slightly indurated, erythematous, pruritic plaque.1 This patient's eruption was asymptomatic, diffuse, and predominantly confluent.
A drug reaction may manifest as a bilaterally symmetrical eruption involving most or all of the body's surface area. The history will include use of a medication started approximately 10 days before the eruption (unless there has been prior exposure), and the eruption is typically pruritic.2,3 Although this patient did have a diffuse, bilaterally symmetrical eruption, it was asymptomatic and there was no history of newly initiated medication.
SCLE is more common in women. Typically there is a mildly symptomatic erythematous, scaling eruption commonly involving sun-exposed regions including the head, neck, upper trunk, arms, and dorsum of the hands. Histologic and laboratory testing help to confirm the diagnosis.4 This patient is male, the eruption involved non-light-exposed regions of the body, and the histologic evaluation was not consistent with SCLE.
The patient was diagnosed as having leprosy, or Hansen's disease, and was admitted to the hospital for evaluation and initiation of treatment.
Leprosy is found worldwide, including in the United States. In 2004, 23 states and Puerto Rico reported a total of 131 cases, 106 of which were in persons born abroad.5 Of the 25 endemic
leprosy cases reported, 10 were in Texas and 4 were in Louisiana.5 Over the past 30 years, the number of newly documented cases of leprosy in this country has remained relatively unchanged.5 The average length of time to diagnosis in the United States is 2 years.6
Etiology Leprosy is caused by Mycobacterium leprae, an acid-fast bacillus.7 Although it may gain entry through abraded skin, it is presumed to be more commonly transmitted between humans by droplet nuclei, as the nasal mucosa is frequently involved. Despite the public's trepidation, most exposed persons will not develop the disease. 6,8 Leprosy has been documented in wild armadillos and potentially could be transmitted from armadillo to human. On subsequent evaluation, this patient admitted to having handled multiple armadillos, most recently 6 to 7 years before the eruption. The incubation period for leprosy ranges from a few months to 40 years, with the average being 2 to 4 years.
Multiple organ involvement Leprosy may involve the skin, peripheral nerves, eyes, mucous membranes, and all visceral organs excluding the GI tract, lungs, and brain. Leprosy is typically a progressive disease, and the extent of involvement is determined by the host's ability to mount an effective cellular immune response to M leprae. The degree of this response determines a patient's clinical presentation and classification.3