CASE PRESENTATION
A 5-year-old, male neutered, American Staffordshire mix presented to the Midwestern University Companion Animal Clinic (MWU CAC) for evaluation of an acute development of labored breathing after having been previously diagnosed with presumptive immune-mediated hemolytic anemia (IMHA) that was treated with multimodal immunosuppressive therapy. The presumptive diagnosis of IMHA was made at MWU CAC a month prior to the current presentation according to the previously published consensus statement based on the presence of severe regenerative anemia (hematocrit 19%; RI, 36-60) with spherocytosis and a positive saline agglutination test as well as hyperbilirubinemia.1 His work up at the time had included repeated complete blood counts, biochemical evaluation with serum chemistries, urinalysis, thoracic radiographs, abdominal radiographs, abdominal ultrasound, SNAP 4Dx test (IDEXX Laboratories, Inc., Westbrook, ME), and babesia titers (Protatek, Mesa, Arizona). The IMHA was presumed to be non-associative based on that work up. However, a complete work up based on consensus guidelines to more definitively rule out associative IMHA was not performed. Ongoing medications at the time of his last presentation included oral cyclosporine at 5.4 mg/kg once daily, oral prednisone at 1.1 mg/kg once daily, oral clopidogrel at 1.0 mg/kg once daily, oral clindamycin at 12.3 mg/kg twice daily, and oral enrofloxacin 11.1 mg/kg once daily. Until 8 days prior to the last presentation, the patient had been receiving oral cyclosporine at 5 mg/kg twice daily. He had been receiving oral prednisone at a dose of 1.5 mg/kg daily after initial diagnosis, which, after two weeks of therapy, had been decreased to the 1.1 mg/kg daily dose due to a stable hematocrit and medication side effects. Clindamycin was started 6 days prior to the last presentation after an acute onset of paw swelling and self-trauma to digits 3 and 4 of the right manus. Based on gross evaluation of the digits during physical exam, primary consideration for the digital lesions was given to opportunistic bacterial osteomyelitis and cellulitis secondary to immunosuppression. No abnormalities with his digits had been noted on any examination prior to that time. The day prior to his final presentation, enrofloxacin was added to the patient’s antimicrobial regimen due to progression of the digit lesions. Due to rapid clinical decline, further cytological work up of that lesion was not pursued prior to broadening the antimicrobial regimen.
Results of physical examination included a rectal temperature of 101.4°F, heart rate of 140 beats per minute, resting respiratory rate of 80 breaths per minute, body condition score of 7/9, and quiet to dull mentation. Increased respiratory effort, moderate labored breathing, and muffled heart sounds were also noted. Pain was elicited on palpation of the right manus, which was edematous and erythematous throughout, with open ulceration of digit 3 and mild serosanguineous discharge from nail beds of digits 3 and 4 (Figure 2).
Cytologic smears of the discharge and fine needle aspirates from digits 3 and 4 were evaluated. Nucleated cells were found individually and in intermediate to large aggregates that were often associated with extracellular hyphal structures. The hyphae were irregularly septate, exhibited acute branching and rarely would have large, round, bulbous ends that contained fine green to black pigmentation (Figure 1). The predominant cell population consisted of numerous degenerate neutrophils and fewer moderate to markedly vacuolated macrophages that occasionally exhibited leukophagia and erythrophagia. There were occasional multinucleated giant cells seen on scanning. The digit cytology was interpreted as marked pyogranulomatous inflammation with intralesional dematiaceous fungal hyphae.
A CBC (Advia 2120i Hematology System) from the previous day revealed a hematocrit of 33% (RI, 36-60), platelet count of 338 K/μL (RI, 170-400), an increased mean cell volume of 82 fL (RI, 58-79), a reticulocytosis of 188 K/μL (RI, 0-0), a leukocytosis of 37.4 x 103 μL (RI, 4-15.5) characterized by a marked total neutrophilia of 29,546 (RI, 2,060-10,600) with a left shift (bands 5,984/μL, RI, 0-300). No spherocytes were reported at that time. Serum biochemistry profile through Antech Laboratories from two days prior revealed an increased alanine transferase of 531 IU/L (RI, 12-118), alkaline phosphatase of 4813 IU/L (RI, 5-131), gamma-glutamyl transferase of 212 IU/L (RI, 1-12), a mild hyperbilirubinemia of 0.7 mg/dL (RI, 0.1-0.3), and a mild total hypocalcemia of 8.6 mg/dL (RI, 8.9-11.4).
Thoracic point of care ultrasound revealed bilateral, severe pleural effusion and pericardial effusion. Cytologic samples of the pleural and pericardial fluid showed numerous degenerate to poorly preserved neutrophils. There were moderate numbers of moderately vacuolated macrophages that occasionally contained phagocytized cellular debris. Both the pericardial and pleural fluid contained moderate numbers of extracellular fungal hyphae (Figure 2) that were often surrounded by degenerate neutrophils and fewer macrophages. The hyphae exhibited predominantly tapered ends with occasional end branching. The hyphae were septated and the septations varied in length () and minimal to mild variation of septae width (). The hyphae exhibited acute branching. Given the difference of fungal morphologies between lesions of the digit and chest, concern for a mixed fungal infection was suspected and culture and PCR were recommended for further evaluation.
Given the poor prognosis, the owner elected palliative care, and euthanasia was performed the following day after respiratory signs recrudesced. A necropsy was performed. During gross examination, liver, kidney, lung, pleural and pericardial fluid, and nail bed samples were submitted for fungal culture and mycologic assessment. The thoracic cavity contained approximately 2 liters of serosanguineous fluid (Figure 2B). Affecting approximately 80%, the pulmonary pleura and mediastinum were markedly thickened with multifocal to coalescing, white-tan, firm plaques and nodules. The pericardium was diffusely and markedly thickened with a pyogranulomatous inflammation and contained approximately 110 ml of red serosanguineous fluid (Figures 2C and 3). The epicardium was also multifocally thickened, rough, and irregular with the same white to tan nodules (Figure 2C). Examination of the abdomen showed multiple, fairly demarcated, white, firm nodules ranging from 0.1 to 0.3 cm in diameter and affecting approximately 5% of the renal cortices bilaterally. Examination of the right, distal forelimb revealed markedly edematous, firm, red digits 3 and 4. An open 1.0 x 0.6 cm wound was noted on the medial aspect of the right front 3rd digit with pink, purulent exudation. There was a small amount of tissue loss around the nail bed of the right front 4th digit with a small amount of yellow-white fluid (Figure 2A).
Significant histopathologic findings included severe, fibrinonecrotizing, pyogranulomatous dermatitis with intralesional and intravascular brown-pigmented septate fungal hyphae and conidia, necrotizing vasculitis, and fibroplasia of the nail beds of digits 3 and 4 of the right forelimb. Similar severe, fibrinonecrotizing, pyogranulomatous pneumonia, pleuritis, pericarditis, and nephritis with intralesional fungal hyphae that exhibited different morphology from hyphae seen on digits 3 and 4, fibroplasia, and serosanguineous effusion were also noted (Figures 1 and 2). Fungal cultures were obtained from samples taken from the visceral organs (lung, liver, and kidney) and presumptively identified as Aspergillus terreus by matrix-assisted laser desorption ionization time-of-flight (MALDI-ToF MS). Another culture of a dematiaceous fungus was isolated from nail beds of digits 3 and 4 of the right front limb and was identified by MALDI-ToF MS as Curvularia lunata . A culture slant of the presumptive Aspergillus terreus UTHSCSA DI20-341 isolate obtained from the lung was submitted for species confirmation to the Fungus Testing Laboratory at the University of Texas Health Science Center at San Antonio (FTL).