Post-Traumatic Primary Cutaneous Cryptococcosis Presenting as a Chronic Refractory Forearm Ulcer with Polymicrobial Coinfection: An mNGS-Assisted Case Report and Literature Review
TL;DR
PCC should be considered in chronic post-traumatic ulcers, with systematic evaluation for extracutaneous involvement before establishing a primary cutaneous diagnosis, according to a 52-year-old male farmer with type 2 diabetes who developed chronic refractory ulcers on the right forearm following suspected insect-bite trauma.
Abstract
Abstract Primary cutaneous cryptococcosis (PCC) is a rare infection caused by direct inoculation of Cryptococcus through disrupted skin. We report a 52-year-old male farmer with type 2 diabetes but no HIV infection or known major immunosuppressive disease who developed chronic refractory ulcers on the right forearm following suspected insect-bite trauma. Cryptococcus neoformans was isolated from cutaneous specimens. Probe-capture metagenomic next-generation sequencing (MetaCAP) of the ulcer tissue additionally detected C. neoformans at 202 reads per million (RPM), accounting for 91.98% of the fungal sequences, with a reported confidence of 99%. Histopathology demonstrated an infectious granuloma, while bacterial culture identified methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase-producing Escherichia coli. Chest computed tomography and cerebrospinal fluid investigations did not support pulmonary or central nervous system cryptococcosis. Liposomal amphotericin B was discontinued because of acute kidney injury, and subsequent fluconazole plus flucytosine treatment resulted in reduced exudation, granulation tissue formation, and partial ulcer healing. PCC should be considered in chronic post-traumatic ulcers, with systematic evaluation for extracutaneous involvement before establishing a primary cutaneous diagnosis.