Nannizziopsis guarroi infection in 2 Inland Bearded Dragons (Pogona vitticeps): clinical, cytologic, histologic, and ultrastructural aspects

Abstract

Chrysosporium-related infections have been increasingly reported in reptiles over the last 2 decades. In this report, we describe clinical, cytologic, histopathologic, and ultrastructural aspects of Chrysosporium-related infection in 2 Inland Bearded Dragons (Pogona vitticeps). Case 1 was presented for an enlarging raised lesion over the left eye and multiple additional masses over the dorsum. Case 2 was submitted to necropsy by the referring veterinarian for suspected yellow fungus disease. Impression smears of the nodules in case 1 revealed granulomatous to pyogranulomatous inflammation and many septate, variably long, 4-10 μm wide, often undulated hyphae, and very rare conidia. Postmortem impression smears of the superficial lesions of case 2 contained large numbers of solitary conidia and arthroconidia and low numbers of hyphae with similar morphology to case 1. Histopathology of the 2 cases revealed severe, multifocal, chronic, ulcerative, nodular pyogranulomatous dermatitis, with myriad intralesional septate hyphae, and arthroconidia. Fungal culture and molecular sequencing in both cases indicated infection with Nannizziopsis guarroi.

What's your diagnosis? Skin impression smear from a Bearded Dragon

“…Yellow Fungus Disease is a significant cause of dermatitis in reptiles and a leading cause of mortality in captive Bearded Dragons. N guarroi is a contagious fungus acting as primary pathogen using keratin of the outer stratum corneum as a substrate, which results in yellow skin lesions, and focal to multifocal dermatitis characterized by vesicles, ulcers, crusts, and necrosis, most commonly on the head, and can invade deeper in the dermis or disseminate into deeper tissues . Ultimately, the infection often results in fatal systemic disease, and prompt diagnosis and treatment are important .…”

“…Ultimately, the infection often results in fatal systemic disease, and prompt diagnosis and treatment are important . As described in an earlier case report, cytologic examination of impression smears is a preliminary diagnostic tool with variable identification of pyogranulomatous to granulomatous inflammation and fungal hyphae and conidia . However, the gold standard is a combination of biopsy with histologic examination, culture at the proper temperature and incubation period, and PCR .…”

“…However, the gold standard is a combination of biopsy with histologic examination, culture at the proper temperature and incubation period, and PCR . Histologic examination typically reveals granulomatous dermatitis with intralesional arthroconidia and hyphae with variable epidermal hyperkeratosis and ulceration . Periodic acid Schiff and Gomori's methenamine silver stains can help identify fungal structures .…”

“…Periodic acid Schiff and Gomori's methenamine silver stains can help identify fungal structures . Of note, despite recent identification of N guarroi as the typical causative agent of YFD in captive Bearded Dragons, this disease is often still attributed to or referred to as the Chrysosporium anamorph of Nannizziopsis vreisii (CANV) or Chrysosporium guarroi …”

“…N guarroi is a contagious fungus acting as primary pathogen using keratin of the outer stratum corneum as a substrate [1][2][3] , which results in yellow skin lesions, and focal to multifocal dermatitis characterized by vesicles, ulcers, crusts, and necrosis 1,2,4,5 , most commonly on the head, and can invade deeper in the dermis or disseminate into deeper tissues. 1,2,5 Ultimately, the infection often results in fatal systemic disease, and prompt diagnosis and treatment are important. 2,4 As described in an earlier case report, cytologic examination of impression smears is a preliminary diagnostic tool with variable identification of pyogranulomatous to granulomatous inflammation and fungal hyphae and conidia.…”