Disseminated phaeohyphomycosis in a dog

Novel Curvularia species causing disseminated phaeohyphomycosis in a dog

Phaeohyphomycosis is an uncommon disease caused by dematiaceous fungi that is almost exclusively found in immunocompromised dogs. Here we describe the case of a dog treated with prednisone (1.1 mg/kg/day) and cyclosporine (11.2 mg/kg/day) for immune thrombocytopenia that developed cutaneous/subcutaneous lesions affecting both forelimbs 29 days after initiation of immunosuppression. The owner elected conservative outpatient treatment that consisted of wound care, antibiotics, mirtazapine, maropitant, and a dose reduction of prednisone (0.3 mg/kg/day) in lieu of biopsies or cultures. The dog was subsequently euthanized 13 days later because of an acute onset of increased respiratory rate and effort, obtunded mentation, and an inability to ambulate. Postmortem examination revealed widespread fungal dissemination in the heart, pericardium, intercostal muscles, lymph nodes, skin, subcutis, kidneys, lungs, pleura, and nasal cavity. Histopathology of the widespread plaques and nodules revealed fungal hyphae that were 4-8 µm in diameter, pigmented, variably septate, non-parallel, and toruloid with acute branching and occasional terminal bulbous dilations up to 20 µm in diameter, resembling chlamydoconidia. Yeast-like cells had a thick, variably pigmented wall and internal, foamy to granular, pale amphophilic contents. Fungal culture of swabs from the right elbow subcutaneous granulomas and from the left lateral pleural nodules yielded pure growth of Curvularia sp. Genomic DNA was extracted from harvested mycelia and molecular sequencing confirmed the presence of a novel Curvularia sp., C. arizonensis.

Cutaneous and visceral phaeohyphomycosis in an immunocompetent golden retriever

A 3-year-old castrated male golden retriever was presented for evaluation of 2 cutaneous masses along the abdominal midline and a 6-month history of progressive lethargy and inappetence. Two years earlier, the dog underwent a gastrotomy to retrieve a foreign object and recovered uneventfully. Fluid aspirated from the lesions was culture-negative for aerobic and anaerobic bacterial growth. Abdominal ultrasound demonstrated a large intra-abdominal mass with apparent communication with the cutaneous lesion, along with gossypiboma from the previous laparotomy. Neoplasia or a sterile abscess were suspected. Exploratory laparotomy was performed and revealed that the intra-abdominal mass was adhered to the abdominal midline and the greater curvature of the stomach. The masses and affected portions of the body wall and stomach were resected and histopathology was consistent with phaeohyphomycosis. Antifungal therapy with voriconazole (6.3 mg/kg, PO, q12h) was initiated. At 1 mo after surgery, all clinical signs had resolved. At 4 and 7 mo after surgery, the dog continued to thrive despite 2 small masses, seen on abdominal ultrasound imaging on the intra-abdominal midline, suggestive of reoccurrence. Continued voriconazole therapy was administered in lieu of further surgical excision. One year after surgery, the masses were no longer present on ultrasonographic evaluation. Phaeohyphomycosis is a rare, opportunistic fungal infection that typically affects the dermis and subcutis of immunocompromised dogs. This is the first report of phaeohyphomycosis in an immunocompetent dog and involving the dermis, subcutis, and abdominal viscera. Key clinical message: This case adds to the very limited literature on phaeohyphomycosis in dogs and illustrates that surgery could be a risk factor for infection, even in dogs with no known underlying disease or immunodeficiency.

A case of Exophiala dermatitidis-induced phaeohyphomycosis in a cat with multiple intra-abdominal masses

Pus discharge containing black granular materials (1-2 mm in diameter) was found in the abdominal skin of a 13-year-old sterilized female cat. Abdominal ultrasonography revealed a large intra-abdominal mass with abundant blood flow beneath the skin lesion. Laparotomy revealed a large mass that adhered to the spleen and left kidney. Similar small lesions were found in the abdominal wall and mesentery. The masses were surgically removed along with the spleen and kidney. Histopathologically, the mass lesions consisted of granulomas with lesional pigmented fungi, and the cat was diagnosed with phaeohyphomycosis. Uisng genetic analysis, the Exophiala dermatitidis was identified as the causative pathogen.

Eumycetoma and disseminated phaeohyphomycosis in a Sumatran tiger

A 16-y-old female Sumatran tiger (Panthera tigris sumatrae) was evaluated for hyporexia. Examination revealed chronic kidney disease and a large subcutaneous axillary mass with draining tracts that contained numerous small black grains. Histologic examination revealed the presence of intralesional fungal hyphae. Persistent hyporexia and pyogranulomatous disease, as well as progressive cachexia and azotemia occurred despite treatment, and euthanasia was performed. Disseminated phaeohyphomycosis was diagnosed on postmortem examination, additionally affecting various lymph nodes, the nasal cavity, mesenteric adipose tissue, abdominal aorta, pericardium, and kidney. Fungal culture from a deep-tissue sample isolated a pure growth of Curvularia sp., a dematiaceous opportunistic fungus able to cause eumycetomas and/or phaeohyphomycosis. Phaeohyphomycosis is a rare but emerging condition, not previously reported as disseminated disease in an exotic carnivore, to our knowledge. Aggressive systemic antifungal treatment was unsuccessful, likely complicated by diagnostic challenges and concurrent renal disease. The presence of a swelling with abundant grains exiting draining tracts should direct clinicians to the diagnosis of a mycetoma, warranting early and aggressive treatment.

Diagnosis, treatment, and outcome in a dog with systemic Mycoleptodiscus indicus infection

Objective

Describe the diagnosis, clinical course, and management of a dog with systemic Mycoleptodiscus indicus infection.

Case Summary

A 5‐year‐old male neutered Giant Schnauzer presented with left eye anterior uveitis, peripheral lymphadenopathy, hyperglobulinemia, anemia, and thrombocytopenia. A diagnosis of M. indicus infection was made based on histopathology and PCR. Treatment with itraconazole and terbinafine resulted in resolution of the hyperglobulinemia, anemia, thrombocytopenia, and peripheral lymphadenopathy. No evidence of fungal organisms was identified on lymph node, liver, or ocular histopathology after 7 months of treatment.

New or Unique Information Provided

This case is the first report of a systemic M. indicus infection in an apparently immunocompetent dog. Clinical resolution was achieved with systemic itraconazole and terbinafine.

Brainstem phaeohyphomycosis due to Curvularia lunata (Cochliobolus lunatus) in a cat

A 13-year-old female neutered domestic short-hair cat was presented with chronic progressive vestibular ataxia, lethargy and anorexia. Clinical examination revealed bilateral mucopurulent nasal discharge. Neurological examination revealed obtundation, a right head tilt, ambulatory tetraparesis, generalised vestibular ataxia, decreased postural reactions in all limbs, right Horner's syndrome, spontaneous conjugate jerk rotatory nystagmus and right positional ventral strabismus. Neuroanatomical localisation was observed in the right central vestibular system. Computed tomography revealed a solitary ill-defined contrast-enhancing mass lesion at the level of the right cerebellopontine angle. Cerebrospinal fluid (CSF) analysis revealed mild mononuclear pleocytosis and fungal elements. CSF culture was positive for Curvularia spp. Further tests for underlying diseases were all negative. The cat was treated with antibiotic and antifungal treatment, but it deteriorated rapidly and was euthanased. Necropsy of the brainstem mass lesion revealed pyogranulomatous inflammation. Panfungal polymerase chain reaction (PCR) targeting the internal transcribed spacer (ITS) region and subsequent sequencing identified Curvularia lunata in the formalin fixed brain tissue. This is the first report of brainstem phaeohyphomycosis by Curvularia lunata (Pleosporales) in a cat. In addition, this is the first report among animal and humans where fungal elements of Curvularia lunata were found in the CSF cytology. Opportunistic fungal pathogens should be always considered within the differential diagnoses list in cats with neurological signs and advanced imaging findings compatible with solitary mass lesions in the brain. In feline patients with pyogranulomatous meningoencephalitis and a suspicion of a fungal aetiology, panfungal PCR for the ITS region and sequencing should be performed regardless of the absence of fungal elements in histopathology.

DERMATITIS AND RHINOSINUITIS CAUSED BY CURVULARIA SPECIES IN A CHINESE GORAL (NAEMORHEDUS GRISEUS)

Curvularia spp. are globally distributed saprophytic fungi, classified in the literature as dematiaceous, or darkly pigmented fungi. These fungi have been increasingly recognized as causing cutaneous, ocular, respiratory, and central nervous system infections in humans, but have been infrequently documented as pathogens in the veterinary literature. A 5-yr-old male Chinese goral (Naemorhedus griseus) presented with bilateral fungal dermatitis of the pinnae, and subsequent pyogranulomatous rhinosinusitis. Clinical signs included epistaxis, mucosanguineous nasal discharge, and dyspnea. Sequential histologic examinations of cutaneous and nasal lesions revealed pyogranulomatous inflammation with extracellular and phagocytized nonpigmented yeasts. Fungal culture and polymerase chain reaction identified Curvularia sp. The absence of pigmentation in tissue in this case suggests that pigmentation may not be a consistent histologic finding for this fungus, emphasizing the importance of molecular identification to prevent misidentification. Despite intensive interventions in this goral, the disease progressed, and was ultimately fatal.

Disseminated melanized fungal infection due to Cladosporium halotolerans in a dog coinfected with canine adenovirus-1 and canine parvovirus-2

This report presents the pathologic findings associated with disseminated infection due to Cladosporium halotolerans in a dog that was simultaneously infected with canine adenovirus-1 (CAdV-1) and canine parvovirus-2 (CPV-2). A 12-year-old, mixed breed dog, with a clinical history of neurological manifestations was submitted for routine autopsy due to poor prognosis. The principal pathologic findings were mycotic necrotizing nephritis, hepatitis, and splenitis with embolic dissemination to the brain resulting in mycotic necrotizing meningoencephalitis, ventriculitis, choroid plexitis, and obstructive hydrocephalus associated with intralesional and intravascular septate pigmented fungi. PCR and sequencing of the ITS region of fungi revealed that the intralesional fungal organisms had 82% nucleotide identity with members of the Cladosporium sphaerospermum complex of organisms. However, a PCR assay and sequencing of the beta tubulin gene confirmed that the organism identified in this dog had 100% nucleotide sequence identity with C. halotolerans. Using immunohistochemistry, intralesional antigens of CAdV-1 were identified within the epithelial cells of the liver and lungs; there was positive immunolabeling for CPV-2 antigens in degenerated cardiomyocytes. These findings confirmed the active participation of C. halotolerans in the development of disseminated cladosporiosis in this dog and represent a rare occurrence of concomitant infection with CAdV-1 and CPV-2.

Sterile Pyogranulomatous Dermatitis and Panniculitis

Canine sterile pyogranulomatous dermatitis and panniculitis is an infrequently described syndrome. No autoantigen, or exogenous antigen, inflammatory stimulus has been identified. This syndrome is characterized by pyogranulomatous nodules, plaques, and ulcers of variable extent and severity. Prodromal and concurrent nonspecific clinical and hematologic signs of inflammation may occur. This waxing and waning condition is typically responsive to systemic immunomodulation. Lifelong therapy may be required to prevent relapse. Differential diagnoses include bacterial and fungal nodular dermatoses, neoplasia, and cutaneous reactive histiocytosis. Diagnosis is achieved via diagnostic exclusion of infectious causes and supportive histopathology findings.

Opportunistic Fungal Infections in Small Animals

Opportunistic fungal infections have long been recognized as rare causes of disease in immunocompetent dogs and cats. Recently, the escalating use of multiagent immunosuppression protocols (especially those that include cyclosporine) has resulted in an increased number of patients with opportunistic fungal infection encountered by small animal practitioners and has altered the typical case phenotype. Based on histologic and cytologic features such as pigmentation, hyphal diameter, and distribution in tissue, these opportunistic mycoses can be placed into categories such as phaeohyphomycosis, hyalohyphomycosis, and eumycotic mycetoma. This review aims to summarize the clinical presentations, methods for diagnosis, treatment recommendations, and prognosis for both immunocompetent and immunosuppressed patients with opportunistic fungal infections. An example case description is included to illustrate the most common current clinical presentation.

Therapy of Non-Dermatophytic Mycoses in Animals

This review focuses on aspects of antimycotic therapy specific to veterinary medicine. In the first part, drug availability, limited mostly by economic consideration but also by clinical applicability and specific adverse effects, is described for polyenes, 5 fluorocytosine, azoles, echinocandins and terbinafine. In the second part, current knowledge and experience in the treatment of selected fungal infections are overviewed. These mycoses include disseminated mold infections in small animals (dogs and cats) and avian species, upper respiratory tract infections of small animals (sino-nasal and sino-orbital aspergillosis) and horses (guttural pouch mycosis), eumycetoma, infections caused by dimorphic fungi, (blastomycosis, histoplasmosis, coccidioidomycosis, paracoccidioidomycosis and sporothrichosis) and by yeasts and yeast-like microorganism (Cryptococcus spp. and Malassezia pachydermatis).