Rare Dermatological Infections - a Retrospective Study of Five-YearExperience in Three Major Reference Hospitals in Costa Rica

Abstract

Objective: Rare cutaneous infections, such as nontuberculous mycobacterial infections, chromoblastomycosis, and sporotrichosis, represent a significant challenge for diagnosis and treatment in tropical regions. In Costa Rica, recent literature on these conditions is limited and consists mainly of small case series published since the year 2000. The aim of this study was to describe the epidemiological and clinical profile, the diagnostic methods, the therapeutic strategies employed, and the comorbidities associated with confirmed cases of cutaneous nontuberculous mycobacterial infections, chromoblastomycosis, and sporotrichosis treated at Hospital México, Hospital Rafael Ángel Calderón Guardia, and Hospital San Juan de Dios between 2019 and 2023. Methods: A retrospective descriptive study was conducted based on the review of medical records, pathology reports, and microbiology registries from the three centers. Patients older than 18 years with diagnoses confirmed through histological, microbiological, or molecular methods were included. Cases without diagnostic confirmation or with insufficient information were excluded. Demographic variables, comorbidities, trauma history, anatomical location, diagnostic methods, isolated species, treatment regimens, and treatment duration were collected. Frequencies, percentages, and confidence intervals were calculated using statistical analyses performed with the R software. The study was approved by the institutional ethics committee and received an exemption from informed consent. In total, 95 patients were included. Results: In the group of nontuberculous mycobacterial infections, which comprised 20 patients, females predominated, and a high proportion of cases was associated with aesthetic procedures such as lipotransfer and abdominoplasty. Most patients had a history of trauma, and the gluteal region was the most frequent anatomical site affected. Mycobacterium abscessus was the most common isolated species. Among the 33 cases of chromoblastomycosis, there was a predominance of male patients and older age at diagnosis. The upper and lower extremities were the most frequently affected sites. Fonsecaea pedrosoi was the most frequently identified agent, and three patients developed squamous cell carcinoma on chronic lesions. Among the 12 cases of sporotrichosis, male patients were also predominant, with greater involvement of the upper extremities, and Sporothrix schenckii was the most common isolated species. Histological studies were the most frequently used diagnostic method in chromoblastomycosis and sporotrichosis, whereas microbiological confirmation was essential in nontuberculous mycobacterial infections. Treatments included prolonged combinations of antibiotics for mycobacterial infections, systemic antifungal agents, and physical therapies for chromoblastomycosis, and itraconazole and saturated potassium iodide solution for sporotrichosis. Treatment duration was longest in chromoblastomycosis, reaching several years in some cases. Conclusions:. In conclusion, this multicenter retrospective study shows that rare dermatological infections continue to represent a relevant clinical challenge in Costa Rica, with distinct epidemiological profiles depending on the causative agent. Nontuberculous mycobacterial infections demonstrated a shift toward risk factors associated with invasive cosmetic procedures, while chromoblastomycosis persists as a chronic, long-evolving mycosis linked to rural exposure and carrying a risk of complications such as cutaneous carcinoma. Sporotrichosis, in turn, retains its classic clinical features, although with signs of earlier diagnosis and shorter treatment durations compared with historical series. Overall, these findings highlight the need to strengthen clinical suspicion, improve access to microbiological and histopathological diagnostic methods, and promote preventive and therapeutic strategies adapted to the regional context.