Despite negative special stains, an infectious cause was still suspected. Oral doxycycline monohydrate 100 mg twice daily, oral fluconazole 200 mg daily, and econazole cream 1% were prescribed because of concern for mycobacterial infection and initial growth of Candida parapsilosis in the swab culture.
A punch biopsy also was performed at this time for both repeat histopathologic analysis and tissue culture. Follow-up appointments were scheduled every 2 weeks. Staining by AFB of the repeat histopathologic specimen was negative.
The patient demonstrated symptomatic and aesthetic improvement (Figure 1B) during consecutive regular follow-up appointments while culture results were pending. No lesions appeared above the left elbow and she had no lymphadenopathy. Results of blood chemistry analyses and complete blood cell count throughout follow-up were normal.
The final tissue culture report obtained 7 weeks after initial presentation showed growth of M haemophilum despite a negative smear. The swab culture that initially was taken did not grow pathogenic organisms.
The patient was referred to an infectious disease specialist who confirmed that the atypical mycobacterial infection likely was the main source of the cutaneous lesions. She was instructed to continue econazole cream 1% and was given prescriptions for clarithromycin 500 mg twice daily, ciprofloxacin 500 mg twice daily, and rifampin 300 mg twice daily for a total duration of 12 to 18 months. The patient has remained on this triple-drug regimen and demonstrated improvement in the lesions. She has been off methotrexate while on antibiotic therapy.
Patient 2
A 79-year-old man with a medical history of chronic lymphocytic leukemia, basal cell carcinoma, and squamous cell carcinoma presented with a nonhealing, painful, red lesion on the left forearm of 1 week’s duration. Physical examination revealed a violaceous nontender plaque with erosions and desquamation that was initially diagnosed as a carbuncle. The patient reported a similar eruption on the right foot that was successfully treated with silver sulfadiazine by another physician.
Biopsy was performed by the shave method for histologic analysis and tissue culture. Doxycycline 100 mg twice daily was prescribed because of high suspicion of infection. Histologic findings revealed granulomatous inflammation with pseudoepitheliomatous hyperplasia, reported as squamous cell carcinoma. A second opinion confirmed suspicion of an infectious process; the patient remained on doxycycline. During follow-up, the lesion progressed to a 5-cm plaque studded with pustules and satellite papules. Multiple additional tissue cultures were performed over 2 months until “light growth” of M haemophilum was reported.
The patient showed minimal improvement on tetracycline antibiotics. His condition was complicated by a photosensitivity reaction to doxycycline on the left and right forearms, hands, and nose. Consequently, triamcinolone was prescribed, doxycycline was discontinued, and minocycline 100 mg twice daily and ciprofloxacin 500 mg twice daily were prescribed.
Nine months after initial presentation, the lesions were still present but remarkably improved. The antibiotic regimen was discontinued after 11 months.