[Cutaneous Cryptococcus neoformans Infection Mimicking Necrotizing Fasciitis in a Myelofibrosis Patient Receiving...

Cryptococcus neoformans is an encapsulated opportunistic yeast widely distributed in the environment and classified as critical-priority fungal pathogen by the World Health Organisation due to its high mortality and limited access to timely diagnosis and effective treatment. Infection is typically acquired via inhalation, with the primary pulmonary focus often remaining asymptomatic. Particularly in individuals with impaired cell-mediated immunity, it may disseminate hematogenously to central nervous system (CNS), skin and other organs. Cutaneous cryptococcosis is a rare clinical manifestation and in most cases, represents secondary involvement of disseminated disease. Its clinical presentation is highly variable and may mimic cellulitis, abscesses, ulcers or necrotizing soft-tissue infections, posing significant diagnostic challenges. Ruxolitinib is a Janus-kinase inhibitor used to treat myelofibrosis and polycythemia vera. By suppressing interferon-γ and interleukin-12-mediated immune responses, it impairs macrophage activation, reduces T-helper-1 cell responses, suppresses natural-killer cell function, and regulates hematopoietic activity. However, these immunomodulatory effects predispose patients to invasive opportunistic infections, particularly fungal infections. In the literature, cryptococcal infections associated with ruxolitinib have been reported in a limited number of case reports, most commonly involving the pulmonary and/or central nervous system. Cutaneous involvement is exceedingly rare, and to date, no cases from Türkiye have been reported. In this case report, a 67-year-old woman with myelofibrosis who had been receiving ruxolitinib therapy for three-years and developed cutaneous cryptococcosis infection mimicking necrotizing fasciitis, accompanied by asymptomatic pulmonary involvement was presented. Despite broad-spectrum antibacterials, a small papule on the medial thigh rapidly progressed over 25 days, with severe disproportionate pain raising suspicion of necrotizing fasciitis. On admission, physical examination revealed an 8×8 cm ulcerative tissue defect on the left thigh, with surrounding erythema, ecchymosis, desquamation and hemopurulent discharge. Magnetic resonance imaging demonstrated findings suggestive of necrotising soft-tissue infection, prompting urgent surgical intervention. Intraoperatively, diffuse inflammation and patchy necrotic areas were observed and surgical debridement followed by vacuum-assisted wound closure was performed. Microbiological cultures of deep-tissue specimens yielded C.neoformans and the pathogen was confirmed by matrix-assisted laser desorption/ ionisation-time-of-flight-mass spectrometry (MALDI-TOF-MS). Antifungal susceptibility testing showed minimum inhibitory concentrations of 0.5 µg/mL for amphotericin B and 4 µg/mL for fluconazole. Histopathological examination demonstrated yeast cells within a background of suppurative inflammation and focal necrosis. Although the patient had no respiratory symptoms, chest computed tomography revealed a cavitary pulmonary nodule consistent with fungal infection. Bronchoalveolar lavage cultures showed no microbial growth. Evaluation for central nervous system involvement resulted negative for India-ink staining and cerebrospinal fluid multiplex polymerase chain reaction (PCR) test. These findings were considered consistent with systemic cryptococcosis involving the skin and lungs. Antibacterials were discontinued and intravenous liposomal amphotericin-B plus fluconazole was initiated. After central netvous system involvement was excluded, sequential therapy with fluconazole was planned. Ruxolitinib dose was adjusted by haematology. Significant clinical improvement was observed in the early phase of treatment and pain however, the patient died due to acute pulmonary embolism. This case highlights a rare cutaneous presentation of ruxolitinib-associated cryptococcosis and emphasizes the importance of clinical awareness for opportunistic fungal infections in immunosuppressed patients.