Retroperitoneal Abscess Associated With a Migrating Grass Awn in a Cat: Treatment With Omentalization and Grass Awn Removal

An 18-month-old domestic short hair male castrated cat presented with a history of fever of unknown origin of 1-year duration. Abdominal ultrasound revealed a mixed echogenicity mass. Cytological examination of the fluid obtained through fine needle aspiration was consistent with a retroperitoneal abscess. The cat underwent a midline celiotomy and the abscess was opened, lavaged, and omentalized. Antibiotics were also administered. Two months after surgery, the cat represented with a fluctuant swelling in the right flank region at the lumbodorsal triangle. Abdominal and mass ultrasound showed a mixed echogenicity swelling in the right flank. Under gas anesthesia, the swelling was surgically explored and a 0.4 cm long grass awn was found and removed. Telephone communication with the owners 6 months after surgery found the cat to be free of clinical signs.     

Uterine malignant mixed Müllerian tumor (Metaplasic carcinoma) in the cat: clinicopathologic features and proliferation indices

A homologous malignant mixed Müllerian tumor of the uterus occurring in an 8-year-old Persian cat was described with regard to its clinical and pathologic features. A polypoid multinodular mass of the right uterine horn was shown by an ultrasound examination. Grossly, the right uterine horn was enlarged because of a vegetative and infiltrating tumor, grayish-white in color, that penetrated the uterine wall to the level of the perimetrium. Many metastatic nodules were found in abdominal and thoracic cavities. Histologically, the neoplasm had both carcinomatous and sarcomatous components and was diagnosed as an uterine malignant mixed Müllerian tumor. This is the fourth case reported in cats. The histologic features and proliferation rate of this tumor were similar to the corresponding human neoplasms, which occur mainly in postmenopausal women. The possible hormone dependence of the tumor is briefly discussed.     

Metastatic neuroendocrine carcinoma of aortic body origin in a cat

An 8‐year‐old, female spayed Domestic Shorthair cat was presented to the Auburn University Emergency and Critical Care service for evaluation of pleural effusion and a suspected intrathoracic mass. Computed tomography was performed which confirmed the presence of a large intrathoracic mass, likely heart‐based. Fine‐needle aspirates were obtained and a cytologic diagnosis of a neuroendocrine tumor was made. Treatment with toceranib phosphate was briefly attempted at home by the owners. The cat died at home approximately 6 weeks after diagnosis. Necropsy and subsequent histopathologic examination revealed a metastatic neuroendocrine carcinoma of aortic body origin. Aortic body tumors are extremely rare in cats and to the authors’ knowledge, a neuroendocrine carcinoma of aortic body origin with distant metastases has not yet been reported in a cat.     

Anterior uveal spindle cell tumor in a cat

Purpose To describe a case of anterior uveal spindle cell tumor in a cat with features similar to spindle cell tumor of blue eyed dogs. Methods A 10‐year‐old female spayed domestic short‐haired cat was referred for an iris mass OS. The mass was solitary, nodular, nonpigmented, located medially, and causing dyscoria. A diagnosis of a benign epithelial tumor was suggested by a FNA of the mass. The cat was lost to follow‐up for 2 years, after which time she re‐presented with glaucoma, blindness and grossly evident iridal mass enlargement OS. Transconjunctival enucleation was performed and the globe submitted for histopathology. Results Histopathology of the enucleated globe revealed the superior iris to be infiltrated and effaced by a large population of neoplastic spindle cells. The cells were arranged in streams and bundles and exhibited Antoni‐A and Antoni‐B tissue patterns, which are characteristic of Schwann cell tumors. Mitotic figures were rare and cellular pleomorphism moderate. Immunohistochemical staining was positive for S‐100 protein and glial fibrillary acidic protein (GFAP), and negative for Melan‐A. Interestingly, there was no histological evidence of glaucoma. Conclusions Based on its histopathologic characteristics, this iris tumor was diagnosed as a Schwann cell variant of a peripheral nerve sheath tumor (PNST) closely resembling the spindle cell tumor of blue‐eyed dogs. Anterior uveal PNST has not been previously reported in cats to the authors’ knowledge. The presence of Antoni type A and type B tissue patterns along with immunohistochemical staining may facilitate a diagnosis of PNST and rule out malignant melanoma.     

Nasal swelling due to plasma cell infiltrate in a cat without plasma cell pododermatitis

A cat with an upper respiratory infection was presented for examination. Close examination of the face revealed a firm, haired rounded swelling on the bridge of the nose. Serum protein electrophoresis demonstrated a mild hypergammaglobulinaemia. The cat tested negative for feline immunodeficiency virus. Skin biopsy of the nasal lesion revealed nodular angiocentric infiltrates in the deep dermis and subcutis. The mixed infiltrate had numerous plasma cells. Presence of calicivirus antigen could not be demonstrated within the skin lesion by immunohistochemical staining. The cat was treated for upper respiratory infection and 1 month later the nasal lesion had resolved. A firm and rounded swelling over the bridge of the nose may be a feline cutaneous plasmacytic reaction pattern.     

Insulinoma in a cat

A 14-year-old domestic shorthair cat was presented with hypoglycaemia and seizures of several weeks duration. Bloodwork revealed hypoglycaemia (1.83 mmol/l; reference range 4.22-8.05 mmol/l) with concurrent normal insulin levels (171 pmol/l; reference range 72-583 pmol/l). An insulinoma was suspected and medical and dietary management were attempted with minimal success. An exploratory laparotomy was performed and a single, well-defined mass was found within the left lobe of the pancreas. The mass was removed and histologically classified as an islet cell carcinoma, consistent with an insulinoma. The cat had an episode of presumed postoperative pancreatitits, but recovered with appropriate treatment. The cat has had no clinical signs of recurrence of greater than 32 months postsurgery. There are only four cases of insulinoma in cats reported in the literature. All prior insulionomas reported were in older cats and were malignant in character, which is similar to the reports in the dog. This case is unique because of the apparent lack of local recurrence and development of metastatic disease, leading to the prolonged survival.     

Paraneoplastic leukocytosis with mature neutrophilia in a cat with pulmonary squamous cell carcinoma

A 13-year old cat had 3-day duration of vomiting, lethargy, and anorexia. A complete blood count revealed a severe neutrophilia (126.9 x 10(3) cells/microl). Thoracic radiographs demonstrated a large solitary lung mass. A bone marrow aspirate documented myeloid hyperplasia. A left intercostal thoracotomy was performed and left cranial and caudal lung lobectomies were performed in order to remove the mass in its entirety. Histological diagnosis was squamous cell carcinoma of the lung. Following surgery, the severe neutrophilia began to decrease. It was in the normal range approximately 6 weeks postoperatively. The presence of a primary lung tumor combined with a mature neutrophilia with resolution following surgical resection suggests a paraneoplastic syndrome.     

An unusual case of feline leukemia and an associated syncytium-forming virus.

A 3-year-old female Siamese cat was admitted to a local animal hospital with a history of recent extreme lethargy and anorexia. A hemorrhagic tumor was removed from an area of oral buccal skin and diagnosed histopathologically as lymphosarcoma. Rapid physical deterioration occurred, and the cat became moribund 2 weeks after surgical operation. Necropsy revealed at least 200 spherical hemorrhagic neoplastic nodules attached to the omentum, mesentery, and peritoneum. Examination of histopathologic sections confirmed the striking characteristics of an extremely vascular and highly invasive malignant lymphoma, which was designated feline tumor No. 01 (FeT-01). There was no evidence of peripheral blood leukemia. Electron microscopic examination of tumor tissue revealed numerous viral particles having characteristics common to both feline leukemia virus (FeLV) and feline syncytium-forming virus (FeSFV). Primary cells and cultures propagated from tumor tissue were found to be negative or weakly positive for group-specific (gs) antigen by radioimmunoassay but strongly positive when assayed by indirect immunofluorescence. Co-cultivation of cells from tumor tissue, with normal prescreened feline embryo cells, revealed the presence of numerous FeSFV-like viral particles in the absence of C-type virus. A FeSFV was isolated from these passaged cells, with characteristics similar to FeSFV isolates previously described in the literature. The apparent presence of FeSFV in lymphosarcomatous tissue and the apparent absence of FeLV C-type particles in passaged cells indicate the need to make a more intensive study of the FeSFV group of viruses and the possible etiologic relationship to feline malignancies.     

Malignant peripheral nerve sheath tumour of the urinary bladder in a cat

A 14-year-old domestic shorthair cat presented with a 5-month history of urinary incontinence and inappro-priate elimination. Ultrasonography revealed a well-marginated, vascular mass of mixed echogenicity ex-tending from the dorsal wall of the urinary bladder into the lumen. Partial cystectomy was performed for re-moval of the urinary bladder mass; histopathological evaluation revealed a spindle cell neoplasm with a prominent palisading pattern. Histomorphologic features and immunohistochemical demonstration of vimentin, glial fibrillary acidic protein and S-100 protein, combined with negativity for smooth muscle actin and desmin were consistent with malignant peripheral nerve sheath tumour. This case report describes a novel location of malignant peripheral nerve sheath tumour; to the authors' knowledge, the bladder has not been described as a site of origin in the cat or any other domestic species.     

Primary chondrosarcoma in the skull of a dog

Chondrosarcoma of the skull is a rare primary malignant tumor that is slow-growing, but locally aggressive. A 5-year-old, golden retriever was presented to our hospital with a swelling in the left side of her head, and the swelling had slowly enlarged over the previous month. There were no significant changes on the neurological examination. A computed tomography scan revealed a large mass involving bone destruction and prominent matrix mineralization. T1-weighted magnetic resonance imaging showed a slightly low-signal intensity area and a T2-weighted image revealed marked, high-signal intensity. There was compression of the adjacent brain parenchyma. Histopathological examination confirmed the lesion to be a chondrosarcoma.     

Malignant melanoma in pleural effusion in a 14-year-old cat

CASE DETAILS: A 14-year-old female cat presented with signs of respiratory distress. Pleural fluid was found on radiographic assessment. Cytologic evaluation of the fluid revealed malignant melanocytosis. The cat had a previous history of a recurrent malignant melanoma near the base of the right ear. Due to declining clinical condition, the cat was euthanized. CLINICAL SIGNIFICANCE: Cutaneous malignant melanomas (or melanosarcomas) are uncommon neoplasms in cats, and knowledge is limited. As far as the authors are aware, there are no previous reports in the veterinary literature of malignant melanocytes being identified in pleural effusion in cats, as they have in dogs. This report suggests that, despite conflicting information in the literature regarding the clinical behavior of cutaneous melanomas in cats, these tumors are capable of recurrence and metastasis. Aggressive treatment may be necessary even, as in this case, if the tumor is well differentiated on histopathology.     

Of all the nerve! A subcutaneous forelimb mass on a cat

A 16-year-old, male, neutered cat had a 2.5 X 1.5 cm mass on the medial aspect of the right carpus. Cytologic examination of a fine-needle aspirate of the mass indicated a markedly pleomorphic population of plasmacytoid to histiocytic-appearing cells. The cytologic diagnosis was malignant neoplasia of probable mesenchymal or round cell origin. The right forelimb was surgically removed and the scapular, axillary, and prescapular lymph nodes were excised. Malignant fibrous histiocytoma was tentatively diagnosed histologically; however, the tumor cells subsequently were found to be negative for histiocytic (MAC 387, antitrypsin), T-cell (CD3), and B-lymphocyte (immunoglobulin light chains, Ly 5/CD45R) markers, and positive for glial fibrillary acidic protein, vimentin, and S-100. Based on the immunohistochemical results, the diagnosis was modified to malignant peripheral nerve sheath tumor (PNST). Six months after surgery, the cat was reported to be well and had no evidence of metastasis. PNSTs are rare tumors in cats, and are considered as synonymous with schwannomas, neurofibrosarcomas, and hemangiopericytomas. In this cat, the plasmacytoid and pleomorphic appearance of the PNSTcells in cytologic and histologic specimens was unusual, and made it difficult to reach an accurate diagnosis without immunocytochemistry.     

Co-existing squamous cell carcinoma and hemangioma on the ocular surface of a cat

A 14-year-old spayed female domestic short-haired cat was presented for evaluation of a mass in the right eye. Ophthalmic examination revealed a blind right eye and presence of two distinct masses: a pink and a red-to-brown mass, the latter occupying most of the cornea and part of the conjunctiva. Exenteration was performed under general anesthesia, and the ocular tissues were processed routinely for histopathology. Upon microscopic examination, a malignant epithelial neoplasm and a benign vascular neoplasm were present in the cornea. The conjunctiva and the third eyelid were also affected. Upon immunohistochemistry, the epithelial tumor was positive for cytokeratin and negative for vimentin and the endothelial tumor was negative for cytokeratin and positive for vimentin. A diagnosis of squamous cell carcinoma (SCC) and hemangioma was made. The SCC was affecting the cornea, bulbar conjunctiva (lateral and inferior) and the base of the third eyelid, whereas the hemangioma was affecting the cornea and medial limbus. To the authors' knowledge, this is the first report of concomitant SCC and hemangioma affecting the ocular surface in a cat.     

Progesterone receptors in feline mammary adenocarcinomas

Estradiol and progesterone receptors were measured in tumor cytosols from 3 intact and 4 neutered female cats with spontaneously occurring mammary adenocarcinomas. Serum from 2 of the intact cats which had been in estrus 4 and 4 to 6 weeks before tumor excision contained progesterone concentrations of 16.2 and 2.2 ng/ml, respectively; serum progesterone in the other cats was less than 2 ng/ml. Estradiol receptors were not detected in any cytosols. Progesterone receptors were detected in all of the cytosols, in concentrations ranging from 4.0 to 11.7 (mean = 7.2) fmol/mg of protein. Scatchard plot analysis of tumor cytosol from an 8th cat with mammary adenocarcinoma revealed presence of high affinity progesterone binding with a dissociation constant (Kd) of 3.47 nM. Tumor receptor content could not be correlated with stage of the estrous cycle nor with whether the cat was intact or neutered.     

Malignant peripheral nerve sheath tumor arising from the spinal canal in a cat

A 10-year-old female mongrel cat with back pain was brought to the Nihon University Animal Medical Center. Palpation demonstrated a mass in the back region. Radiography revealed partial destruction of the processus spinosus and the arch of the T8 and T9 vertebrae. On magnetic resonance imaging, the mass was found to have compressed the spinal cord and extended to the outside of the spinal canal. We performed extirpation of the mass, and confirmed that it arose from the spinal canal. Histopathologically, the mass was a malignant peripheral nerve sheath tumor.     

Histiocytic sarcoma in the tarsus of a cat

A 12-year-old Persian cat was examined for a firm swelling of the right tarsal region and enlargement of the corresponding right popliteal lymph node. Cytologic evaluation demonstrated a population of malignant cells consistent with large cell lymphoma. Necropsy revealed a multi-lobulated subcutaneous mass involving the tarsus with some extension into adjacent deep muscular tissue. Histologically, the mass was composed of round cells with eosinophilic cytoplasm and pleomorphic anisokaryotic nuclei. Evidence of articular and nodal infiltration by these cells was observed. Differential diagnoses included synovial sarcoma and histiocytic sarcoma. Neoplastic cells were negative for cytokeratin, CD79a, and CD3 and positive for CD18, vimentin, lysozyme, and alpha-1-antitrypsin, most consistent with a diagnosis of histiocytic sarcoma. This is the first report of a histiocytic sarcoma involving a joint of a cat. The final diagnosis was based on the light microscopic appearance in combination with the immunohistochemical stains.     

Sysmex XT‐2000iV scattergram analysis in a cat with basophilia

A 13‐year‐old female Domestic Shorthair cat was presented to the Veterinary Teaching Hospital of the University of Milan for an interscapular mass suspected to be a mesenchymal malignant tumor. A preoperative CBC performed with Sysmex XT‐2000iV showed leukocytosis with neutrophilia and eosinophilia. The Sysmex WBC/DIFF scattergram showed an additional, well‐separated cluster of events between the neutrophil, eosinophil, and lymphocyte clusters. Blood smear evaluation revealed the presence of a significant number of basophils; thus, it was hypothesized that the additional cluster could represent the basophilic population. A second CBC, 24 days later, showed the same pattern on the WBC/DIFF scattergram in the absence of leukocytosis and neutrophilia. After surgical excision of the mass, a definitive diagnosis of feline injection site sarcoma was made. To the author's knowledge, there are no previous reports about the identification of feline basophils in the WBC/DIFF scattergram of Sysmex XT‐2000iV.     

Olfactory neuroblastoma in a cat

CASE SUMMARY: A 12.5-year-old castrated male domestic shorthair cat was presented for evaluation of dyspnea. Physical examination suggested upper airway disease. Computed tomography revealed the presence of a nasopharyngeal mass. Biopsies obtained via rhinoscopy led to a diagnosis of olfactory neuroblastoma. CLINICAL CHALLENGES: Olfactory neuroblastoma (or esthesioneuroblastoma) is a rare malignant neoplasm that arises from olfactory neuroepithelium. It was first described in human medicine in 1924. Clinical signs are variable, and diagnosis may prove challenging as this tumor, which is a differential for spontaneous intranasal tumors in cats, may be mistaken for poorly differentiated carcinomas or round cell tumors. Given its rarity, treatment options for this neoplasm have not been thoroughly evaluated and there is no standard treatment protocol. LITERATURE REVIEW: A review of veterinary and human literature is provided, encompassing clinical signs, staging and grading systems, treatment options and prognostic factors.     

Conjunctival dacryops in a domestic shorthair cat

A 1-year-old spayed female domestic shorthair cat with a 1-week history of a conjunctival mass located in the dorsolateral quadrant of the right eye was presented to a referral hospital. Ophthalmic examination revealed a pink, fluctuant, and non-painful cystic swelling of the upper right palpebral conjunctiva. An ocular ultrasound confirmed the presence of a fluid-filled cystic structure that extended into the temporal orbit. The histopathology of the excisional biopsy revealed multiple cysts lined by ductal epithelium along with dilated lacrimal gland ducts and lymphocytic nodules adjacent to the dorsal lacrimal gland; consistent with a diagnosis of dacryops.     

Functional cystic thyroid adenoma in a cat

A 9-year-old cat with hyperthyroidism was referred for radioactive iodine treatment. The cat also had a ventral cervical mass that the owners reported had been present for several years and had increased in size during the past few weeks. On physical examination, the mass was found to have caused lateral displacement of the trachea, esophagus, jugular vein, and common carotid artery. The mass was aspirated and was determined to be cystic in nature. Concentrations of thyroid hormones in the cystic fluid were similar to serum concentrations, and nuclear scintigraphy revealed thyroactive tissue lining the cyst wall. Magnetic resonance imaging suggested that the cyst originated from the right lobe of the thyroid gland. The cat was treated with sodium iodide I 131 but died 4 days later, presumably as a result of aspiration of gastric or esophageal contents. A necropsy was not performed, but histologic examination of a biopsy specimen of the mass indicated that it was a cystic thyroid adenoma.