A 54-year-old male farmer from Eirunepé (Amazon, Brazil) presented with a 30-year history of pink nodules and plaques on his left thigh and knee. In 2016, excisions of the lesions was performed at his hometown, but recurrence was observed after 3 months. Physical examination revealed papules, plaques, and keloid-like nodules on his left thigh and knee and some scarring areas (Fig 1). Direct mycological examination using potassium hydroxide was performed (Fig 2). A punch biopsy was also performed and histopathological examination using Grocott stain was performed (Fig 3).
Fig 1.
Fig 2.
Fig 3.
Question 1. What is the most likely diagnosis?
-
A.
Keloid
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B.
Lobomycosis
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C.
Blastomycosis
-
D.
Chromoblastomycosis
-
E.
Wade histoid leprosy
Answers:
-
A.
Keloid – Incorrect. Lesions look like keloid, but in this case, there was no history of previous trauma. Multiple lesions are uncommon in keloid. Histological findings: Thickening of collagen bundles in nodular arrangement. No fungal cells are observed on direct mycological examination.
-
B.
Lobomycosis – Correct. Keloid-like lesions are very common in lobomycosis. Lobomycosis may present as verrucous, ulcerative, atrophic, or keloid-like. Direct mycological examination reveals oval or round yeast cells with single or multiple budding type reproduction in chain arrangement.1,2
-
C.
Blastomycosis – Incorrect. Clinically, cutaneous lesions are not keloid-like. The skin is usually involved, following dissemination of pulmonary infection. Blastomyces dermatitidis is a thermally dimorphic fungus, which grows as a mycelial form unlike Lacazia loboi, which has never been cultivated. Histologically, blastomycosis often shows neutrophils and pseudoepitheliomatous hyperplasia. In lobomycosis, epidermal atrophy, flattening of rete ridges, xantomized histiocytes, and numerous fungal cells in chains are frequently visualized.
-
D.
Chromoblastomycosis – Incorrect. Lesions are usually verrucous with presence of black dots. Medlar bodies are seen by direct mycological examination. In the Amazon region, culture is usually positive for Fonsecaea pedrosoi, while the etiological agent of lobomycosis (Lacazia loboi) has not been isolated yet.
-
E.
Wade histoid leprosy – Incorrect. Clinically, this condition is characterized by the presence of numerous indurated, infiltrated, keloid-like or xanthoma-like nodules with no preferred location. It may be due to drug resistance or mutation in strains of Mycobacterium leprae. Histology reveals abundant number of bacilli and elongated or fusiform histiocytes, similar to neurofibroma.3
Question 2. Which of the following is a severe complication associated with this disease?
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A.
Chronic renal failure
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B.
Systemic dissemination
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C.
Basal cell carcinoma
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D.
Sepsis
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E.
Squamous cell carcinoma
Answers:
-
A.
Chronic renal failure – Incorrect. Usually, there is no systemic involvement in lobomycosis. No association of lobomycosis with chronic renal failure has been reported.
-
B.
Systemic dissemination – Incorrect. Lobomycosis usually affects only the skin. Eventually, it may involve lymph nodes, which was not the case in the present patient.2,4
-
C.
Basal cell carcinoma – Incorrect. However, there are some case reports with association of lobomycosis and squamous cell carcinoma. No case of basal cell carcinoma and lobomycosis has been described.5
-
D.
Sepsis – Incorrect. While secondary infection may occur in lobomycosis, there is no case report describing development of sepsis in literature.
-
E.
Squamous cell carcinoma – Correct. Malignant transformation of lobomycosis to squamous cell carcinoma has been described and is probably due to fibrosis and chronic inflammatory reactions.5
Question 3. Which of the following is the most effective treatment for this disease?
-
A.
Fluconazole
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B.
Intravenous amphotericin B
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C.
Cryotherapy
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D.
Radiotherapy
-
E.
Combination of surgery and systemic antifungal drugs.
Answers:
-
A.
Fluconazole – Incorrect. Case reports using fluconazole in lobomycosis have not shown efficacy.
-
B.
Intravenous amphotericin B – Incorrect. There are no reports in the literature describing the use of intravenous amphotericin B. However, the authors of this article opted for a new approach to treatment involving a combination of surgery, CO2 laser, oral itraconazole (100 mg/day), and intralesional injections of amphotericin B with clinical and histological improvement of the lesions at 1 year follow-up.4
-
C.
Cryotherapy – Incorrect. Results using isolated cryotherapy for treating lobomycosis are poor. Some case reports have revealed partially successful results with the combination of clofazimine and cryotherapy. The fibrosis and deep penetration of subcutaneous tissue reduce the efficacy of cryotherapy.4
-
D.
Radiotherapy – Incorrect. There are no reports in the literature showing sufficient efficacy of radiotherapy in the treatment of lobomycosis.
-
E.
Combination of surgery and systemic antifungal drugs – Correct. Treatment of lobomycosis remains a challenge. A combination of surgical excision and systemic antifungal drugs, such as itraconazole associated or not with clofazimine, and, more recently, with posaconazole, appears to give better results. In this study, intralesional injections of amphotericin B enhanced the result.
Conflicts of interest
None declared.
Footnotes
Funding sources: None.
References
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