Sporotrichoid Nodules in a Farmer From an Endemic Leishmaniasis Area
A 34-year-old man from a rural area near Isfahan, Iran, presents with three painless ulcers on the left forearm that appeared 8 weeks after outdoor work and sandfly bites. The lesions are 1–2 cm with raised violaceous borders and central crust; a fourth firm nodule lies along the lymphatic tract toward the epitrochlear area. He has no fever, and HIV testing is negative. He applied topical betamethasone 0.1% to the lesions for 3 weeks before presentation. A smear taken at another clinic shows no Leishman–Donovan bodies. Complete blood count and liver and kidney function are normal. He works as a farmer and cannot attend frequent infusions. He asks whether the nodules mean the infection has spread and whether he needs systemic treatment.
1. What is your differential diagnosis, and how do you proceed diagnostically after a negative smear?
Read the worked answer
Differential
The main diagnosis is cutaneous leishmaniasis with lymphatic spread. The sporotrichoid pattern also raises sporotrichosis, atypical mycobacterial infection, nocardiosis, tularemia, and, less likely, deep fungal infection. In an endemic Iranian focus, leishmaniasis remains the leading possibility.
Why the smear was negative
A negative smear does not exclude leishmaniasis. Topical betamethasone for 3 weeks can reduce parasite load and inflammation. The sample may also have been taken from crust or necrotic tissue rather than the active raised border, and low-parasite-load species such as Leishmania tropica can be missed.
Next steps
Take a punch biopsy from the active border of a lesion, not the center. Send tissue for Giemsa stain, parasite culture on NNN medium, and polymerase chain reaction (PCR); PCR is the most sensitive single test. Also send tissue for bacterial and fungal culture and histopathology to evaluate the alternatives. Do not delay treatment solely to repeat smears if the clinical picture is typical.
2. Assuming the PCR confirms Leishmania, how do you choose between local and systemic treatment in this patient?
Read the worked answer
Local versus systemic
Local therapy is appropriate for uncomplicated cutaneous leishmaniasis: a small number of lesions, no facial or mucosal involvement, no immunosuppression, and no large or deeply destructive lesion. This patient has four lesions with a sporotrichoid pattern, which leans toward systemic therapy, but the decision must balance disease severity against his inability to attend daily injections.
Options
- Intralesional meglumine antimoniate: 1–2 mL per lesion weekly for 4–8 weeks. This is effective for uncomplicated lesions and avoids systemic toxicity. It is less practical for multiple lesions and may not adequately treat lymphatic spread.
- Systemic pentavalent antimony: 20 mg/kg/day IM for 20 days, with baseline and weekly ECG, renal, liver, and pancreatic enzyme monitoring. This is preferred for multiple, large, facial, mucosal, or sporotrichoid lesions. It requires daily attendance, which he cannot manage.
- Alternatives: liposomal amphotericin B or miltefosine where available and appropriate. Cryotherapy can be combined with intralesional antimony for small lesions.
Practical plan
Discuss the trade-offs. If he can arrange daily injections, treat systemically because of the sporotrichoid spread. If not, start intralesional therapy under supervision and reassess at 4 weeks; if lesions enlarge or new nodules appear, switch to systemic therapy.
3. Two months later, a new lesion appears on the left cheek near the lower eyelid and is enlarging despite three intralesional injections. What is your next step?
Read the worked answer
Urgent reassessment
A periocular lesion is a special site because of the risk of eyelid necrosis, ectropion, corneal exposure, and disfigurement. Intralesional injections near the eyelid can cause local necrosis and should not be repeated blindly. Assess the conjunctiva, cornea, and nasolacrimal system, and examine the nasal mucosa for mucosal leishmaniasis.
Management
Stop further intralesional injections at that site and refer to an oculoplastic or dermatology team experienced in periocular leishmaniasis. Systemic therapy is generally preferred for facial and periocular disease. Use liposomal amphotericin B or systemic pentavalent antimony according to availability and contraindications, with cardiac and laboratory monitoring. Protect the cornea with lubricants and treat secondary bacterial infection if present. Do not use cryotherapy close to the lid margin.
Follow-up
Photograph and measure the lesion, review at 2–4 weeks, and monitor for mucosal spread. Treatment failure or new lesions despite adequate systemic therapy should prompt confirmation of adherence, species identification if possible, and consideration of an alternative agent.