Pathology in Practice PDF

Pathology in Practice In collaboration with the American College of Veterinary Pathologists History A 6-year-old 40.5-kg castrated male Golden Retriever mixed-breed dog was referred for evalu- ation of seizure activity, blindness, and inappe- tence following a 2-month history of intermittent co...

Pathology in Practice In collaboration with the American College of Veterinary Pathologists History A 6-year-old 40.5-kg castrated male Golden Retriever mixed-breed dog was referred for evalu- ation of seizure activity, blindness, and inappe- tence following a 2-month history of intermittent constipation and lethargy. One month prior to re- ferral, the dog had developed skin lesions. At the time of referral, the dog was being treated with oral carprofen, gabapentin, and fluconazole (dos- es unknown). The dog had no history of clinically relevant illness or injury. It had been transported from Georgia as a puppy and had not traveled out- Figure 1—Images of cutaneous and ocular lesions of side of New England since. a 6-year-old 40.5-kg castrated male Golden Retriever mixed-breed dog evaluated because of seizure activ- ity and signs of blindness and inappetence following a Clinical and Clinicopathologic 2-month history of intermittent constipation and leth- Findings argy. A—Numerous raised, pink, ulcerated cutaneous nodules of various sizes are evident. Similar lesions On presentation, the dog was dull and unwilling multifocally affected the entirety of the body. B—The left eye has multiple conjunctival nodules (asterisks), a to stand but able to walk with support. Propriocep- superficial corneal ulcer ventrally (arrow), and multiple tive deficits were noted in both pelvic limbs. Ulcer- iridal nodules (arrowheads). C—Photograph of the left ated cutaneous nodules of varying sizes were ap- fundus taken after pharmacological pupillary dilation, preciated over the entirety of the body (Figure 1). featuring a swollen optic nerve head and multiple sub- The oral mucosa was multifocally ulcerated, and the retinal nodules of various sizes (double daggers). mandibular and retropharyngeal lymph nodes were markedly enlarged. µL) characterized by mature neutrophilia (22.8 X Menace response and dazzle reflex were ab- 103 cells/µL; RI, 2.8 X 103 to 11.5 X 103 cells/µL) sent, and pupillary light reflexes were severely di- and eosinophilia (3.39 X 103 cells/µL; RI, 0 X 103 minished bilaterally. Multiple conjunctival nodules to 1.4 X 103 cells/µL). A serum biochemical panel were present, several of which appeared to have (Cobas-6000; Roche Diagnostics) revealed moder- abraded the cornea, producing superficial ulcers ate hypoglycemia (52 mg/dL; RI, 67 to 135 mg/ bilaterally. Trace flare was present bilaterally along dL), mildly low BUN (5 mg/dL; RI, 8 to 30 mg/dL) with multiple pale nodules in the right iris. Fundic and creatinine (0.5 mg/dL; RI, 0.6 to 2.0 mg/dL), evaluation revealed multiple raised, pale-pink sub- and hypomagnesemia (1.4 mg/dL; RI, 1.8 to 3.0 retinal nodules and swollen hyperemic optic nerve mg/dL), hypernatremia (159 mEq/L; RI, 140 to 150 heads bilaterally (Figure 1). mEq/L), hyperchloremia (118 mEq/L; RI, 106 to 116 A CBC (ADVIA 2120; Siemens Inc) showed mEq/L), and hypoalbuminemia (2.4 g/dL; RI, 2.8 to moderate leukocytosis (30.84 X 103 WBCs/µL; ref- 4.0 g/dL). Serology (Snap 4Dx; Idexx Laboratories) erence interval [RI], 4.4 X 103 to 15.1 X 103 WBCs/ results were negative for Anaplasma phagocytophi- lum, Ehrlichia canis, and Borrelia burgdorferi anti- Riley K. Aronson, DVM1; David S. Conway, DVM1; Stephanie A. bodies and Dirofilaria immitis antigen. Pumphrey, DVM1; Ramón M. Almela, DVM, PhD1; Adam Powers, Formulate differential diagnoses, then continue BVMS2; Annabelle Burnum, DVM2; Francisco O. Conrado, DVM, MSc2* reading. 1Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 2Department of Comparative Pathobiology, Cummings School Additional Clinical of Veterinary Medicine, Tufts University, North Grafton, MA and Clinicopathologic Findings *Corresponding author: Dr. Conrado ([email protected]) Fine-needle aspirates from cutaneous lesions doi.org/10.2460/javma.22.06.0269 on the face and forelimb were submitted for micro- 1 Unauthenticated | Downloaded 09/25/24 05:51 AM UTC scopic evaluation and appeared cytologically simi- lar (Figure 2). The preparations were moderately cellular, well preserved, and mildly blood-contam- inated on a pale to densely basophilic background with some lysed nuclei and streaming nuclear mate- rial. Abundant yeast organisms were present, scat- tered throughout the smears and frequently found in variably sized clusters. These organisms were round or oval and measured approximately 4 to 8 μm in diameter, with distinct borders and a smooth to wrinkled or folded, variably stained internal structure. These forms were often surrounded by a clear, nonstaining capsule and narrow-based bud- ding was occasionally observed, consistent with Cryptococcus spp. Macrophages were frequently found, often containing phagocytized fungal organ- isms, along with several inflammatory multinucle- ated giant cells. Small, well-differentiated lympho- cytes, plasma cells, and mature, nondegenerate neutrophils were seen less frequently. Figure 3—Postmortem images of the same dog. A— Marked subcutaneous edema is evident, especially in the periorbital and perimandibular regions. B—Multiple coalescing tan subcutaneous granulomas (arrows) are throughout the subcutis, reflected from the dorsal as- pect of the skull, and there is bilateral diffuse atrophy Figure 2—Photomicrograph of a fine-needle aspirate sam- of the temporalis muscles. C—Raised, tan granulomas ple from a facial lesion of the dog in Figure 1. There are nu- are seen across all lung lobes, and the tracheobronchial merous oval yeast organisms (arrows) containing a vari- lymph nodes (asterisk) are extremely enlarged. D—The ably thick, nonstaining capsule and occasionally exhibit- right prescapular lymph node contains coalescing, red ing narrow-based budding, consistent with Cryptococcus to tan nodules that bulged on cut surfaces along the spp. Variably vacuolated macrophages (arrowhead) were node’s periphery. E—Fungal granulomas are within the frequently seen throughout the preparations. Modified cerebellar folia (asterisk) and diffusely throughout the Romanowski stain; bar = 20 µm. meninges (double daggers). H&E stain; bar = 500 µm. F—A large fungal granuloma (asterisk) effaces and com- presses histologically normal thyroid tissue, and multiple A serum latex agglutination test (Idexx smaller fungal granulomas are present. H&E stain; bar Laboratories) was performed for Cryptococcus spp an- = 500 µm. G—A subretinal fungal granuloma (asterisk) tigen and was positive at a 1:32,768 dilution. The dog and infiltration surround the optic nerve (another mani- was subsequently euthanized due to declining condi- festation of meningitis) resulting in retinal detachment tion and poor prognosis. A necropsy was performed. and clinical blindness. H&E stain; bar = 500 µm. H—Yeast organisms within a prescapular lymph node have intense aquamarine staining of their thick, mucopolysaccharide Gross and Histopathologic capsules. Alcian blue stain; pH = 2.5; bar = 50 µm. Findings In addition to the dermatologic and ocular find- cutaneous trunci and temporalis muscles, tongue, ings noted during the antemortem physical exami- spleen, liver, kidneys, lungs, thyroid gland, lymph nation, necropsy revealed marked lymphadenopathy nodes, conjunctiva, irides, choroid, optic nerves, and and multifocal pale nodules in the peripheral lymph brain and meninges (Figure 3). Granulomas were com- nodes, cutaneous trunci and temporalis muscles, posed of epithelioid macrophages with interspersed lungs, and kidneys (Figure 3). A small volume of multinucleated giant cells and neutrophils and with red-tinged fluid was present in the pleural space, and yeast-like organisms seen intra- and extracellularly. mild mucosal hemorrhage was noted in the duode- These measured 5 to 7 µm and were round with a thin num to midjejunum. periodic acid–Schiff stain–positive wall and a thick Microscopically, disseminated granulomas with carminophilic and Alcian blue–positive capsule. Nar- intralesional yeast were present in the skin, subcutis, row-based budding was noted along with occasional 2 Unauthenticated | Downloaded 09/25/24 05:51 AM UTC pseudohyphal structures. Morphological characteris- prior to spread to the CNS.3 Because this dog had no tics were consistent with Cryptococcus spp. history of travel since puppyhood, and because there is a low incidence of cryptococcosis in New England, diagnosis was delayed in this case until the develop- PCR and Sequencing ment of cutaneous lesions. A PCR protocol targeting the 18S small sub- In addition, the dog of this report had no his- unit rRNA gene,1 performed on material scraped tory of underlying immunodeficiency and had not off the cytologic preparations from skin lesions, been treated with immunosuppressive medications yielded an amplification fragment of approxi- prior to onset of clinical signs, further decreasing the mately 380 bp after primer editing. Direct, bidi- initial index of suspicion for systemic mycoses. The rectional sequencing confirmed the presence of a more common C neoformans is generally considered Cryptococcus sp in the sample, with 100% identity to an opportunistic pathogen.2 C gattii, on the other both Cryptococcus neoformans and Cryptococcus hand, has previously been thought to have the abil- gattii (unable to be differentiated on the basis of ity to infect immunocompetent individuals, although the amplified region). recent work suggests that many seemingly immu- nocompetent humans infected with C gattii may in fact have underlying immune deficiencies.11 How- Morphologic Diagnosis ever, most dogs with cryptococcosis lack obvious and Case Summary evidence of immunodeficiency. Genetic differences Morphologic diagnosis: disseminated granu- in host immunity seem to play a role in the devel- lomatous inflammation (eyes, brain, lungs, liver, opment of disseminated cryptococcosis in otherwise spleen, kidneys, muscle, thyroid gland, lymph apparently immunocompetent people, and the same nodes, and skin) with intralesional encapsulated may be true for dogs.11 Cryptococcus spp yeast. Speciation was not performed in this case Case summary: disseminated cryptococcosis in due to poor prognosis and election of euthanasia an apparently immunocompetent dog. shortly after diagnosis. The PCR assay performed on material from the fine-needle aspirates was able to confirm a Cryptococcus sp in the sample, but Comments speciation protocols (ie, targeting the internal tran- scribed spacer gene) were unsuccessful, likely due The gross and histopathologic findings in this re- to the nature of the sample. Speciation could also port are consistent with disseminated cryptococco- be performed by use of culture on growth media sis. The 2 primary disease-causing species of the en- containing specific D-amino acids that enable dif- capsulated haploid saprophytic yeast Cryptococcus ferentiation between C neoformans and C gattii.12 are C neoformans, found worldwide, and C gattii, Given the interest in C gattii as an emerging patho- found largely in the tropics and subtropics but also gen and the minimal documentation of this organ- reported in parts of Europe and the west coast of ism in New England, speciation would have been North America.2,3 C gattii has also been identified in ideal from a public health standpoint. samples from a human patient in New England with- This case serves as a reminder that fungal dis- out a contributory travel history.4 ease should be included as a differential diagnosis in Cryptococcus typically infects the host via the individuals with potentially consistent clinical signs, respiratory tract, later disseminating hematoge- regardless of geographic region, travel history, or nously but, in rare cases, can also infect a host via species. These clinical signs may include weight loss, a damaged skin barrier.3 Cryptococcosis is the most anorexia, altered mental state or change in behavior, common systemic fungal disease in cats but is now coughing, sneezing, epistaxis, stertorous respiration, considered an emerging systemic mycosis in dogs.5 cutaneous or subcutaneous lesions, seizures, visual It has also been documented in numerous other deficits, or ocular lesions. The authors emphasize the mammalian species, including humans.3,6 importance of early sampling of accessible lesions to Dogs are more likely than cats to have CNS in- obtain a timely diagnosis. volvement with profound inflammation and wide- spread disseminated disease, including but not limited to the skin, lymph nodes, nasal cavity, eyes, and vari- Acknowledgments ous parenchymal organs.7 The ocular lesions described No external funding was used for this case. The authors in most canine case reports are characterized by uni- declare that there were no conflicts of interest. lateral or bilateral granulomatous or hemorrhagic exu- The authors would like to thank April Childress and Dr. dative chorioretinitis, with or without retinal detach- Robert J. Ossiboff for assisting with PCR and sequence analysis. ment.8–10 Seizure activity is reported in approximately 43% (9/21) of dogs with CNS cryptococcosis.7 References Early in the disease process, clinical signs may 1. Anderson IC, Campbell CD, Prosser JI. Potential bias of mimic other conditions, and in geographic regions fungal 18S rDNA and internal transcribed spacer poly- where this agent is not endemic, or when affecting merase chain reaction primers for estimating fungal bio- a species in which this disease does not occur fre- diversity in soil. Environ Microbiol. 2003;5(1):36–47. quently, cryptococcosis can be missed. Prognosis is 2. Gerontiti S, Oikonomidis IL, Kalogianni L, et al. 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Sykes JE, Sturges BK, Cannon MS, et al. Clinical signs, zation of D-amino acids as the sole nitrogen source. imaging features, neuropathology, and outcome in cats PLoS One. 2015;10(7):e0131865. doi:10.1371/journal. and dogs with central nervous system cryptococcosis pone.0131865 4 Unauthenticated | Downloaded 09/25/24 05:51 AM UTC