Grouped Indurated Papules on the Arm of a Healthy Child Following Skin Trauma

CASE An otherwise healthy 6-year-old boy presented with grouped skin lesions on the right arm. His mother reported that the lesions had developed 3 months after a skin abrasion while playing in a park on a trip to Morocco, the home country of his parents. Initially, a bacterial skin infection was suspected, and fusidic acid cream was applied without improvement. In a later visit to a different medical practitioner, the lesions were considered as warts, and the patient was referred to dermatology for treatment. On examination, he had numerous grouped indurated erythematous-violaceous papules on the lower arm, some with central crusting (Fig. 1). There were no other remarkable findings on physical examination. The family did not report bleeding or discharge from the lesions at any point from the outset. The boy did not have a fever or other systemic symptoms. Histopathologic examination of the skin biopsy revealed the diagnosis (Fig. 2).FIGURE 1.: Grouped indurated erythematous-violaceous papules on the lower arm, some with central crusting.DENOUEMENT A skin biopsy was performed considering foreign body granuloma, mycobacterial infection, fungal infection and cutaneous leishmaniasis as potential differential diagnoses. Cultures of the skin biopsy for bacteria, mycobacteria and fungi were negative. The histopathology showed a dense superficial and deep dermic inflammatory infiltrate characterized by lymphocytes, histiocytes, multinucleated giant cells and plasma cells (Fig. 2A), as well as numerous intracellular Leishmania spp. amastigotes (Fig. 2B). Leishmania major was identified in the tissue through a polymerase chain reaction. The diagnosis of cutaneous leishmaniasis was established. Given the total area affected, persistence of the lesions, proximity to a joint area and difficulty of intralesional injections for multiple lesions, treatment with intravenous liposomal amphotericin B at a dose of 3 mg/kg for 5 consecutive days and on day 10 was indicated. At the 6-month control visit, the lesions had healed with minimal scarring, and there was no relapse after 1 year of follow-up.FIGURE 2.: Dermic inflammatory infiltrate characterized by lymphocytes, histiocytes, multinucleated giant cells and plasma cells (A), as well as numerous intracellular round bodies (B).Leishmaniasis is a protozoan infection caused by species of the genus Leishmania and transmitted by sandflies. Canids and rodents are the primary reservoirs, except for the species Leishmania donovani and Leishmania tropica, which have a predominantly human reservoir.1,2 The disease is endemic to the Mediterranean Basin, Africa, South Asia and Middle and South America, and its clinical presentation depends on both the species of parasite and the host response.1 Visceral leishmaniasis, the most severe form, is caused mainly by Leishmania donovani in Africa and Asia and Leishmania infantum in the Mediterranean Basin, Middle East, Central Asia and South America and is characterized by fever, hepatosplenomegaly, weight loss and pancytopenia.1,2 In some patients, particularly in those infected with Leishmania donovani, cutaneous sequelae may occur in the form of hypopigmented macules, warty papules or nodules with predominantly facial involvement, which is known as postkala azar dermal leishmaniasis.2 Localized cutaneous leishmaniasis is the most frequent clinical manifestation of Leishmania infection. Typical lesions are crusted ulcers that develop on exposed skin after inoculation.3 In addition to localized cutaneous leishmaniasis, some Leishmania species found in Middle and South America may cause mucosal involvement, presenting as ulcerated lesions of the oral or nasal mucosa with potential cartilage or bone destruction, as well as much rarer forms such as diffuse and disseminated cutaneous leishmaniasis.1–3 Beyond the classic clinical forms, there are less common presentations that may mimic other conditions. Here, we report a pediatric case of cutaneous leishmaniasis that developed after local trauma, clinically mimicking a foreign body granuloma and infections by inoculation. Local trauma such as tattoo, shaving, abrasions and even electrocoagulation have been described as triggers of cutaneous leishmaniasis.4 Bacterial or fungal co-infection may be present in these cases, leading to misdiagnosis and recurrence of lesions despite treatment.5,6 Both aggravation of preexisting lesions and new distant lesions have been reported. Some authors have hypothesized, based on limited evidence in animal models, that patients with cutaneous leishmaniasis may have circulating infected macrophages that are attracted to sites of trauma.7 Suspected visceral leishmaniasis can be confirmed by direct demonstration of Leishmania in tissue specimens, serologic testing and polymerase chain reaction. In the case of children, it is preferable to start by performing microscopy, molecular and serological testing on peripheral blood and reserving bone marrow or lymph node sampling for patients in whom the diagnosis is not confirmed by initial testing.8 In case of clinical suspicion of cutaneous leishmaniasis, full-thickness skin biopsy after removing cellular debris and exudates is the specimen of choice for diagnostic confirmation, as histopathology allows both direct visualization of amastigotes and to rule out other diagnoses.9 The biopsy usually shows a mixed dense granulomatous dermic inflammatory infiltrate composed of lymphocytes, histiocytes and multinucleated giant cells. In the acute phase of the disease, amastigotes are readily visible within histiocytes, and positivity by Giemsa staining with negativity by periodic acid–schiff or methenamine silver stains allows them to be fully distinguished from Histoplasma yeast forms.10 It is recommended to perform cultures to exclude other infectious etiologies, as well as molecular amplification assays because they are the most sensitive diagnostic techniques for leishmaniasis.9 In patients with visceral leishmaniasis, systemic treatment is mandatory. For this purpose, pentavalent antimonial compounds, paromomycin, oral miltefosine and amphotericin B, either alone or in combination therapy, can be used depending on the geographical area and its availability.8 Treatment of skin lesions in immunocompetent persons is indicated when suspected or known to be caused by Leishmania species with increased risk for mucosal leishmaniasis, when lesions do not heal spontaneously or in patients with complex cutaneous leishmaniasis. In this latter group, which includes patients with lesions that are multiple (>5), large (>4 cm) or located on the face, joints or genitalia, systemic treatment is recommended. Therapeutic options include intralesional or intravenous pentavalent antimonial compounds, intravenous amphotericin B, oral miltefosine, and oral antifungal “azole” compounds.9,11 In our patient, for whom intralesional treatment was not practical, we selected the option of intravenous liposomal amphotericin B because of its good risk-benefit ratio and to avoid prolonged hospitalization. As a conclusion, the development of ulcerative or crusted persistent lesions at a site of local trauma, in addition to complications such as infections by inoculation or foreign body granuloma, should also raise suspicion for cutaneous leishmaniasis in endemic areas.