Inflammatory myofibroblastic tumors in two dogs

Intradural-extramedullary inflammatory pseudotumour of the cervical spinal cord of a dog

An 8-year-old mixed-breed dog was presented with cervical hyperesthesia, tetraparesis, and mild proprioceptive ataxia in all four limbs. 3 Tesla MRI showed a dorsal compressive intradural-extramedullary mass at the level of C1-C2, isointense to the gray matter with a hypointense ventral core on T2 weighted images (WI), isointense on T1WI, with a strong and homogeneous contrast enhancement. A C1-C2 partial dorsal laminectomy was performed, and the lesion was removed en bloc. The histopathological and immunohistochemical analysis defined the diagnosis of inflammatory pseudotumor.

Granulation tissue-type hemangioma in a 6-week-old puppy - a case report

BACKGROUND

Hemangioma is a well-known neoplasia in veterinary and human medicine. Several subtypes have been described and are distinguished based on their histologic appearance. The classification schemes of hemangiomas in human and veterinary medicine are different, and various purpose-based schemes can be found in the literature.

CASE PRESENTATION

A six-week-old puppy was presented that suffered from a neoplasia that extended to the musculature of the hind limb. After surgical excision, the mass was submitted for pathohistological examination. The mass was composed of endothelial cells forming vascular slits admixed with a fibrous stroma and spindle cells. Immunohistological examination was positive for factor VIII-related antigen and smooth muscle actin, supporting the diagnosis of hemangioma.

CONCLUSION

The final diagnosis of granulation tissue-type hemangioma was given due to the histological appearance of the neoplasia. Granulation tissue-type hemangioma is a rare subtype of hemangioma. In this case an uncommonly young dog was affected.

Clinicopathologic features and biologic behavior of canine splenic nodules with stromal, histiocytic and lymphoid components

The term fibrohistiocytic nodule has been discouraged in favor of specific pathologic entities, including complex nodular hyperplasia, splenic stromal sarcoma and histiocytic sarcoma. Nevertheless, the diagnosis of splenic lesions with mixed stromal, histiocytic and lymphoid components still remains a challenge due to lack of straightforward histologic criteria. Misestimation of the biologic behavior of these lesions may lead to detrimental consequences on the clinical management of patients. In this study, we retrospectively evaluated the clinicopathologic features and outcome of canine splenic nodular lesions with mixed components, to identify prognostic factors and histologic criteria of malignancy. Thirty-seven cases were included. Immunohistochemistry did not allow for further subclassification. Nine (24.3%) dogs died from disease-related causes after a median of 234 days (range, 48–1,247). One-, 2- and 3-year disease-specific survival rates were 80, 60, and 43%, respectively. When considering nodules with stromal cell atypia and at least one of mitotic count ≥9, presence of karyomegaly/multinucleated cells and lymphoid component <40%, half of these dogs died of disease-related causes with a median disease-specific survival time of 548 days (95% CI, 0-1216). In the remaining dogs, no disease-related death was reported (P < 0.001). Canine splenic nodular lesions with mixed stromal, histiocytic and lymphoid components and histologic criteria of malignancy may behave aggressively, leading to distant metastasis and death. In the absence of further criteria aiding their classification, and to better characterize their biologic behavior, we encourage the distinction of these complex splenic tumors from conventional sarcomas and histiocytic sarcomas.

Retrospective immunohistochemical investigation of suspected non-visceral leiomyosarcoma in dogs

Visceral leiomyosarcoma is well described in dogs, but information about non-visceral locations and prevalence is lacking. The diagnosis of leiomyosarcoma is challenging without a gold standard, and often includes the use of immunohistochemical (IHC) stains. We used defined histopathologic patterns, histochemical staining, and IHC staining for smooth muscle actin (SMA), desmin, and laminin to characterize suspected non-visceral leiomyosarcoma in dogs at a single academic institution. In a retrospective search, we identified 24 dogs with a definitive or suspected histologic diagnosis of leiomyosarcoma in a non-visceral location. Histopathology results and clinical details were obtained. Biopsy sections were reviewed by a single pathologist using standardized histologic criteria, including light microscopic appearance, immunohistochemistry (more than two-thirds of neoplastic cells labeled with SMA and desmin or laminin), and histochemical staining (minimal-to-mild matrix deposition by Masson trichrome). Of the 24 cases of possible non-visceral leiomyosarcomas, 4 were consistent with a definitive diagnosis of non-visceral leiomyosarcoma (3) or leiomyoma (1) based on the established criteria. Only the leiomyoma had more than two-thirds of neoplastic cells label with all 3 markers; all 3 leiomyosarcomas had more than two-thirds of neoplastic cells label with SMA and laminin. Our data highlight the uncommon nature of non-visceral leiomyosarcoma and the importance of IHC for their diagnosis. A definitive diagnosis could not be made based on SMA alone, and desmin was not useful in this cohort. Further studies are needed to clarify the histopathologic, IHC, and clinical features of canine non-visceral SMA-positive mesenchymal tumors.

A Recurrent Inflammatory Myofibroblastic Tumor-like Lesion of the Splenic Capsule in a Kitten: Clinical, Microscopic and Ultrastructural Description

OBJECTIVE

To describe the findings of an unusual splenic tumor in a kitten.

METHODS

A grossly multinodular mass arising from the splenic capsule of a 7-month-old male Havana kitten was echographically detected and surgically removed by splenectomy, then analyzed microscopically and ultrastructurally.

RESULTS

The mass showed features of an inflammatory myofibroblastic tumor.

TREATMENT AND OUTCOME

Two months after surgical excision, the mass recurred in the same intra-abdominal area but disappeared after 2 months of anti-inflammatory therapy. Follow-up at 18 months after surgery revealed resolution of the disease.

CLINICAL RELEVANCE

Inflammatory myofibroblastic tumor in cats have been rarely reported and are usually in the orbital region. In the present report, an unusual multinodular gross presentation, a recurrence over time, and a favorable clinical course, are described.

Imaging and pathological findings of intramedullary inflammatory pseudotumour in a miniature dachshund: a case report

Background

Inflammatory pseudotumours (IPTs) are distinctive lesions consisting of myofibroblastic spindle cells and a variety of inflammatory cells. The aetiology of IPTs is unknown. Reports of IPTs in veterinary medicine have been scarse. Moreover, only one case of intradural extramedullary IPT has been previously reported. In this report, we introduce the first known case of canine IPT, which occurred in the parenchyma of the spinal cord.

Case presentation

A 10-year-old female Miniature Dachshund presented with a 2-month-long history of progressively worsening ataxia and tetraparesis. Neurological examination was consistent with a lesion involving the cervical spinal cord. Magnetic resonance imaging revealed an intradural space-occupying lesion in the region of the fourth cervical vertebra. Dorsal laminectomy and resection of the mass were performed. Histopathological examination revealed the proliferation of immature spindle cells (fibroblasts/myofibroblasts and glial cells) and a highly cellular mixture of neutrophils, macrophages and lymphocytic cells. The mass was located in the parenchyma of the spinal cord and was diagnosed as an IPT occurring in the parenchyma of the spinal cord. No causative pathogen was detected. The dog’s symptoms improved, during the first month after surgery. However, neurological symptoms, such as laboured breathing and dysuria, subsequently worsened and the dog died 42 days after surgery.

Conclusions

The present study describes a canine case of IPT occurring in the parenchyma of the spinal cord. The diagnosis and determination of the site of the mass was difficult solely based on preoperative imaging in the present case. The outcome of this case was poorer than that observed in cases of canine extramedullary IPT and human intramedullary IPT, in which the patients exhibited recovery. The prognosis after surgical resection cannot be decided from the present case alone. However, patients should be monitored for potential serious complications and recurrence.

Evaluation of cytology and histopathology for the diagnosis of canine orbital neoplasia: 112 cases (2004-2019) and review of the literature

OBJECTIVE

To provide an updated overview of canine orbital neoplasia, to compare diagnostic utility of cytology and histopathology, and to evaluate alternative sampling modalities, particularly image-guided core needle biopsy.

PROCEDURES

A medical records search was performed to identify dogs with orbital neoplasia. Data were collected regarding signalment, diagnosis, vision status, imaging modalities, and sample collection methods. A reference population with orbital neoplasia was also identified via literature search for comparison with regard to final diagnosis.

RESULTS

One hundred and twelve dogs met selection criteria. In the study and reference populations, respectively, diagnoses were grouped as follows: mesenchymal tumors 40% and 35%, epithelial tumors 35% and 18%, tumors of neural origin 8% and 37%, and round cell 17% and 10%. The most common diagnoses in the study group were nasal adenocarcinoma, osteosarcoma, lymphoma, and meningioma. Cytology results were available for 47 dogs and histopathology results were available for 95 dogs. Both cytology and histopathology results were available for 30 dogs, in 53% of which results were discordant. Cytology samples were nondiagnostic or provided a diagnosis that was later overturned in 32% of cases in which they were obtained. Results from core needle biopsy samples were nondiagnostic or overturned by surgical biopsy results in only 13% of cases. No significant complications were associated with any sampling method.

CONCLUSIONS

Orbital neoplasia is common in dogs. Histopathology is superior to cytology in providing a definitive diagnosis. Image-guided core needle biopsy appears to be a safe and effective means of obtaining samples.

Inflammatory myofibroblastic tumor of the pancreas in a dog

A large, ill-defined, firm, multinodular mass involving the pancreas was confirmed on postmortem examination of a 5-y-old, male Rottweiler that died following acute respiratory distress syndrome, after a period of anorexia and lethargy. Histologically, the mass consisted of plump spindle cells admixed with a variable number of macrophages, lymphocytes, plasma cells, and neutrophils. Foci of coagulative necrosis and hemorrhage were also observed. Spindle cells strongly reacted to antibodies against vimentin, α-smooth muscle actin, and calponin, whereas desmin was expressed only mildly and focally. Pan-cytokeratin, KIT, glial fibrillary acidic protein, and S100 protein were nonreactive. Variable numbers of MAC 387-positive cells, CD3+ lymphocytes, and numerous blood vessels were also detected throughout the mass. Histologic and IHC findings were consistent with a diagnosis of inflammatory myofibroblastic tumor of the pancreas.

Leiomyoma in the nasal cavity of a dog

A 7-year-old, 34-kg, neutered male Labrador retriever was presented with a 1-year history of intermittent sneezing with occasional left-sided epistaxis. CT revealed a mass in the left nasal cavity. Histopathological analysis of rhinoscopy-guided tissue biopsies was consistent with chronic necrotic and ulcerative rhinitis. Surgical debridement by ventral rhinotomy was subsequently performed and histopathological diagnosis was leiomyoma. Complete resolution of the nasal discharge and reduced sneezing frequency were observed after surgery. Fourteen months postoperatively, CT detected no regrowth of the mass.

Laryngeal paralysis associated with a muscle pseudotumour in a young dog

An 18-month-old male entire Bloodhound dog was presented with a six-week history of progressive inspiratory dyspnoea, stridor, dysphonia and exercise intolerance. CT scan performed elsewhere had revealed the presence of an unencapsulated nodular mass (3x1x5 cm) dorsal to the larynx and first tracheal rings. Laryngoscopy demonstrated the presence of bilateral laryngeal paralysis and distorted laryngeal architecture suggestive of extraluminal compression. Histopathology results of incisional biopsies from the mass were suggestive of a benign non-neoplastic muscular lesion. Surgery was performed to manage laryngeal paralysis and attempt mass excision. A second histopathology examination confirmed an inflammatory and dysplastic lesion suggestive of a pseudotumour. All clinical signs resolved after surgery and at the 13 months follow-up the dog remains asymptomatic. To the authors’ knowledge, this is the first report of a case of laryngeal paralysis caused by a muscle pseudotumour in a young dog.

Idiopathic sclerosing orbital inflammation mimicking a malignant spindle cell tumor in a dog

A dog presented with a retrobulbar mass, diagnosed histopathologically as malignant spindle cell neoplasia. Emergence of analogous findings in the contralateral orbit prompted extended immunohistochemistry of the original mass and reassignment to idiopathic sclerosing orbital inflammation. Early incisional biopsy with extended immunohistochemical analysis should be considered for canine orbital tumors.

Renal leiomyosarcoma in a cat

Renal leiomyosarcoma was diagnosed in a 10-year-old Domestic Shorthair cat with a 3-year history of clinically managed, chronic renal disease. Sudden death was preceded by a brief episode of mental dullness and confusion. At postmortem examination, the gross appearance of the left kidney was suggestive of hydronephrosis, and a nephrolith was present in the contralateral kidney. However, histology revealed an infiltrative, poorly differentiated, spindle cell sarcoma bordering the grossly cavitated area. Neoplastic cells were immunoreactive for vimentin and smooth muscle actin, which led to a diagnosis of renal leiomyosarcoma; neoplastic cells were not immunoreactive for desmin. Leiomyosarcoma arising in the kidney is a rare occurrence in humans and an even rarer occurrence in veterinary medicine with no prior cases being reported in cats in the English literature. The macroscopic appearance of the tumor at postmortem examination was misleadingly suggestive of hydronephrosis as a result of the large cavitation and may be similar to particularly unusual cases of renal leiomyosarcomas in humans that have a cystic or cavitated appearance.

IMAGING DIAGNOSIS - MAGNETIC RESONANCE IMAGING OF INTRACRANIAL INFLAMMATORY FIBROSARCOMA IN A MIXED BREED DOG

An 8-year-old mixed-breed dog presented with progressive behavioral changes and altered mentation. Magnetic resonance imaging (MRI) of the brain revealed an olfactory and frontal lobe extra-axial mass. The mass exhibited the following MRI signal intensity characteristics: T2W mixed, T1W iso- to hypointense, FLAIR hyperintense, and strong contrast enhancement. The mass was removed with cavitronic ultrasonic surgical aspirator (CUSA) assisted neurosurgery. Based on histopathological appearance and immunohistochemistry, the diagnosis of inflammatory fibrosarcoma was made. To our knowledge, this is the first report describing MRI characteristics of intracranial inflammatory fibrosarcoma in the veterinary literature.

An emulsion restores the skin barrier by decreasing the skin pH and inflammation in a canine experimental model

The aim of this study was to investigate the effect of Douxo(®) Calm Mousse (Sogeval, Laval, France) on restoration of the skin barrier in a canine model of barrier disruption. Tape strips were performed, daily for 6 days, on the lateral thorax of five healthy beagle dogs. Douxo(®) Calm Mousse was applied daily for 5 days to one side of the thorax and the opposite side was left untreated. The effects of treatment were evaluated by measurement of transepidermal water loss (TEWL) and pH and by histological assessment of disrupted skin at various times during barrier repair. Although no effect on TEWL was observed, Douxo(®) Calm Mousse maintained an acidic pH after three applications and reduced skin inflammation, which was most pronounced after five applications. The results of the study suggest that Douxo(®) Calm Mousse exerts a beneficial effect on barrier restoration and on markers of inflammation.

Inflammatory myofibroblastic tumour in the nasal cavity of a dog

A 4·5-year-old, female neutered Leonberger was presented with a 2-month history of sneezing, nasal discharge and epistaxis. A presumptive diagnosis of nasal aspergillosis was made based on a suspected (fungal) granuloma on rhinoscopic examination and fungal hyphae on cytological examination. A poor response to targeted therapy was observed and computed tomography 16 months after initial presentation revealed a progressive, locally invasive mass lesion. Histopathological and immunohistochemical analysis of deep surgical biopsies revealed a spindle cell population and a plasma cell rich inflammatory infiltrate, with diffuse expression of vimentin, supporting a diagnosis of inflammatory myofibroblastic tumour. Complete resolution of the nasal discharge and reduced sneezing frequency was reported 9 months post-surgical debridement via rhinotomy. To the authors' knowledge, this is the first report of IMT in the nasal cavity of a dog. IMT should be considered when presented with a nasal mass lesion, particularly if histopathological features and clinical course are inconsistent.

Low-grade myofibroblastic sarcoma of the maxillary region in a dog

A subcutaneous tumour was identified in the maxillary region of a 14-year-old mixed breed dog. This tumour had grown rapidly over 2 weeks. Microscopically, the tumour had ill-defined borders and was composed of bundles and whorls of atypical spindle cells accompanied by abundant collagen fibres. Immunohistochemically, neoplastic cells were immunoreactive for vimentin, α-smooth muscle actin and calponin and negative for S100 protein, von Willebrand factor, desmin and smoothelin. These results suggested that the neoplastic cells were derived from myofibroblasts and that the tumour was a low-grade myofibroblastic sarcoma.

Disseminated pleomorphic myofibrosarcoma in a grizzly bear (Ursus arctos horribilis)

The pathological and diagnostic features of a widely disseminated pleomorphic high-grade myofibroblastic sarcoma are described in a 23-year-old male brown bear (Ursus arctos horribilis). Firm, solid, white to tan neoplastic nodules, often with cavitated or soft grey-red necrotic centres, were observed throughout most internal organs, subcutaneous tissues and skeletal muscles on gross examination. Microscopically, the tumour consisted of pleomorphic spindle cells forming interlacing fascicles with a focal storiform pattern with large numbers of bizarre polygonal multinucleate cells, frequently within a collagenous stroma. Immunohistochemistry, Masson's trichrome stain and transmission electron microscopy designated the myofibroblast as the cell of origin. This is the first case of a high-grade myofibrosarcoma in a grizzly bear.

Characterization of the canine skin barrier restoration following acute disruption by tape stripping

The stratum corneum (SC) forms the main part of the permeability barrier of the skin. In mice and in humans, cutaneous barrier disruption can be generated by removing the SC with tape stripping (TS) and the skin barrier function can be assessed by measurement of transepidermal water loss (TEWL). The aim of the present study was to characterize the skin barrier restoration in the dog following mechanical disruption and to analyse the correlation between the skin barrier recovery and TEWL measurement. Thirty sequential TS were performed on 12 sites on four healthy beagle dogs. The number of TS was chosen to ensure a sufficient barrier disruption with a slow recovery. Skin repair was assessed for 72 h by clinical and histological examinations, and TEWL measurements. The results showed that performing 30 TS was adequate to disrupt the skin barrier in the dog. The homeostatic repair response, initiated in the skin, was rapid and characterized by complete restoration of the SC within 72 h, accompanied by greater basal cell proliferation, and dermal eosinophilic inflammation. TEWL was significantly increased by complete removal of the SC but recovered along with restoration of the SC (Scheffe test, P ≤ 0.05). Characterization of a canine model of barrier disruption and restoration and assessment of the skin barrier function by TEWL measurements could help better understand the events implied in skin barrier function. Development of this canine model is also necessary for future studies on the effects of treatments aimed at restoring the skin barrier.

High-grade myofibroblastic sarcoma of inguinal region in a dog

A subcutaneous tumor in the left inguinal region was present in an 11-year-old female bloodhound. Histopathologically, the tumor showed invasive growth and extensive necroses, and it was composed of spindle-shaped, elongated, and stellate neoplastic cells accompanied by occasional giant cells arranged in fascicular, herringbone, or irregular storiform patterns with abundant production of collagen fibers. The cytoplasm of most tumor cells was positive for vimentin, alpha-smooth muscle actin, and calponin, but was negative for desmin, smoothelin, and S-100. Furthermore, most of the tumor cells were negative for Iba1 while some tumor cells were weakly positive. Thus, this tumor was diagnosed as a high-grade myofibroblastic sarcoma according to the diagnostic criteria for human myofibroblastic sarcomas.

Diagnostic Exercise: oral tumor in an aged mare

A 17-year-old, Thoroughbred mare was presented for necropsy with a large, invasive oral mass determined via immunohistochemistry to be a soft tissue sarcoma of neural origin. Oral sarcomas are rare in veterinary medicine, and to the authors' knowledge, this is the first oral sarcoma of neural tissue origin reported in a horse.

Neurological, imaging and pathological features of a meningeal inflammatory pseudotumour in a Maltese terrier

A five-year eight-month-old Maltese terrier was presented with a 3-week history of progressive paraparesis and pelvic limb ataxia. Neurological examination was consistent with a lesion involving the T3-L3 spinal cord segments. Myelogram and magnetic resonance imaging revealed a spherical, intradural-extramedullary mass lesion at T13/L1. A dorsal laminectomy, durotomy and debulking of the mass were performed. Histopathologic examination revealed a highly cellular tissue, most likely of mesenchymal origin, infiltrated by many lymphocytes, macrophages and neutrophils. The pathological diagnosis of an inflammatory pseudotumour was made. Postsurgical analgesia was achieved with opioids and 2 mg/kg carprofen twice daily for 5 days. When the histopathological diagnosis was made, a tapering course of 1 mg/kg prednisolone twice daily was prescribed, with dose reduction by approximately 50% every 4 to 6 weeks over a 4-month period. Magnetic resonance imaging was repeated at 22, 32 and 85 weeks postsurgery; no signs of regrowth could be detected and the patient recovered with residual mild paraparesis. Inflammatory pseudotumour has not been documented previously at this site in dogs and, although rare, should be considered in the differential diagnosis of a focal mass lesion affecting the spinal cord. Surgical debulking and immunomodulatory therapy can be curative.

Diagnostic features of feline restrictive orbital myofibroblastic sarcoma

A progressive debilitating disease of the orbit and adjacent connective tissues of cats has historically been called feline orbital pseudotumor. The authors reviewed clinical, histopathologic, and diagnostic imaging features of this disease in 12 cases from the Comparative Ocular Pathology Laboratory of Wisconsin. The cats' ages ranged from 7 to 16 years (mean, 10.8 years). All cats had a history of severely restricted mobility of the globe and eyelids with secondary corneal disease. Eleven cats (92%) had concurrent involvement of the contralateral eye and/or the oral cavity. Diffuse scleral or episcleral thickening was seen with computed tomography in all clinically affected eyes. Histologically, an insidious infiltration of neoplastic spindle cells in the orbit, eyelids, and periorbital skin and soft tissues, with collagen deposition and a few perivascular lymphocytes, led to entrapment and restricted mobility of the eyelids and orbital tissues. The tumor failed to form a discrete mass, and it spread along fascial planes to the contralateral orbit and eyelids and/or the lips and oral cavity. In all tested cases (n = 10), neoplastic cells were immunohistochemically positive for vimentin, S100 protein, and smooth muscle actin. The authors adopted the term feline restrictive orbital myofibroblastic sarcoma to reflect the restricted mobility of the eyelids and globe and the imaging and histologic features of an invasive yet low-grade myofibroblastic sarcoma.