Three cases of carcinoid in the equine nasal cavity and maxillary sinuses: histologic and immunohistochemical features

Comparative studies on the histological characteristics of equine nasomaxillary aperture and paranasal sinus mucosa considering topographic and age-related differences

Background

Horses may acquire a range of paranasal sinus diseases. Clinical studies show slight differences regarding anatomical regions and age. Histopathological examination of tissue samples could play an important role in the diagnostic process. Therefore, detailed knowledge of the histological appearance of the paranasal sinus mucosa (PSM) and the nasomaxillary aperture mucosa (NAM) is essential. The objective of this study was to determine topographic and age-related differences within the healthy equine PSM. In addition, we aimed to gain detailed knowledge of the histological appearance of the NAM in comparison to the PSM.

Results

The PSM had an average height of 75.72 ± 44.48 μm with a two-row pseudostratified columnar epithelium of 13.52 ± 4.78 μm. The parameters mucosal height, epithelial height and number of goblet cells revealed significant dependency of the sample site and age group. The maxillary and dorsal conchal sinus showed the highest values for these parameters. In terms of age, younger horses showed a significantly higher total mucosal height in contrast to a significantly lower epithelial height than older horses. Positive correlation was seen between the epithelial height and number of goblet cells. The NAM had an average height of 820.27 ± 653.21 μm. Its pseudostratified epithelium was usually arranged in three rows and had an average height of 44.9 ± 12.78 μm. The number of goblet cells in the NAM was five times higher than in the PSM. Serous glands were found in only 4% of the PSM samples and 100% of the NAM samples.

Conclusions

There are significant histological differences between different paranasal sinus sites and between different groups of age. This may be related to an altered susceptibility for certain pathologies. The striking difference in the histological appearance of the NAM compared to the PSM could be due to an enhanced role in mucociliary clearance. Further studies are necessary to improve the understanding of mucosal function in specific paranasal sinus compartments and mucosal changes generated by different diseases.

Radiographic, computed tomographic and surgical anatomy of the equine sphenopalatine sinus in normal and diseased horses

REASONS FOR PERFORMING STUDY

Knowledge of imaging anatomy, surgical anatomy and disorders affecting the sphenopalatine sinus are currently lacking.

OBJECTIVES

To describe the computed tomographic (CT) and surgical anatomy of the sphenopalatine sinus and diagnosis, treatment and outcome in clinical cases with sphenopalatine sinus disease.

STUDY DESIGN

Cadaver observational study and retrospective case series.

METHODS

The sphenopalatine sinuses of 10 normal cadaver heads were examined with digital radiography, CT and sinoscopic examination prior to anatomical sectioning. Sphenopalatine sinus anatomy was described and compared between cadaver specimens across the imaging modalities. Medical records (January 2004-2014) of cases diagnosed with sphenopalatine sinus disease were reviewed.

RESULTS

The anatomy of the sphenopalatine sinus was variable. The borders of the sphenopalatine sinus were not identifiable on plain radiographs, whereas CT provided useful anatomical information. The palatine portion of the sphenopalatine sinus was consistently accessible sinoscopically and the sphenoidal portion was accessible in 6/10 cadaver heads. Fourteen cases of sphenopalatine sinus disease were identified, presenting with one or more clinical signs of exophthalmos, blindness, unilateral epistaxis or unilateral nasal discharge. Diagnoses included neoplasia (7), progressive ethmoidal haematoma (4), sinus cyst (2) and empyema (1). Computed tomography provided diagnostic information but could not differentiate the nature of soft tissue masses. Standing sinoscopic access to the palatine portion of the sphenopalatine sinus was possible for evaluation, biopsy and resection of abnormal soft tissues. Surgical access to the sphenoidal portion was limited. Eight horses were alive at 1 year after diagnosis, with a worse outcome associated with CT evidence of bone loss and a diagnosis of neoplasia.

CONCLUSIONS

Sphenopalatine sinus disease should be considered a rare cause of the clinical signs described. Knowledge of the anatomical variation of the sphenopalatine sinus is vital for interpreting CT images. A combination of CT and sinoscopy provides the most comprehensive approach for diagnosis and treatment of sphenopalatine sinus disease.

Ocular Pathology

Although not comprehensive of all ocular conditions in the equine species, this article concentrates on various ophthalmic conditions observed in the horse where laboratory diagnostics are recommended. The importance of laboratory diagnostic testing cannot be underestimated with equine ophthalmic disease. In many cases, laboratory diagnostics can aid in obtaining an early diagnosis and determining appropriate therapy, which in turn, can provide a better prognosis. In unfortunate cases where ocular disease results in a blind, painful eye necessitating enucleation, light microscopic evaluation is imperative to determine or confirm the cause of the blindness and provide a prognosis for the contralateral eye.

Computed tomographic appearance of equine sinonasal neoplasia

The computed tomography (CT) features of tumors involving the nasal cavity and/or paranasal sinuses of 15 horses were reviewed. The 15 tumors included five neuroendocrine tumors/neuroblastomas, two undifferentiated carcinomas, two myxosarcomas, and one each of nasal adenocarcinoma, hemangiosarcoma, chondroblastic osteosarcoma, anaplastic sarcoma, myxoma, and ossifying fibroma. All tumors except the ossifying fibroma were iso- or hypoattenuating relative to masseter muscle. Thirteen of the fifteen tumors exhibited moderate or marked osteolysis of adjacent cortical bone and 14/15 were characterized by destructive changes of the nasal turbinates, nasal septum, and/or infraorbital canal. Ten horses had moderate or marked involvement of the cribriform plate and six had clear intracranial extension of the mass. CT features were compared to radiographic findings for 10 horses. A mass was observed in 10/10 radiographic studies and mass within the caudal maxillary sinus (7/8) and rostral maxillary sinus (6/7) was identified correctly in most horses. The radiographs were least sensitive for identifying masses within the sphenopalatine sinus (0/5), cranium (0/4), and retrobulbar space (1/7) compared to CT. The radiographs also underestimated potential features of malignancy, such as severity of osteolysis or osseous production. While radiographs are a useful screening tool for identification of sinonasal masses, CT provides greater information regarding mass extent, features of malignancy, and important prognostic indicators.

Neuroendocrine carcinoma of the apocrine glands of the anal sac in a dog

A perianal subcutaneous tumor involving the anal sac developed in an 8-year-old male mixed Labrador Retriever dog. Histologically, this tumor showed typical features of the solid-type carcinoma of the apocrine glands of the anal sac. However, neoplastic cells were immunoreactive for cytokeratin 8, chromogranin A, vasoactive intestinal peptide, neuron-specific enolase, and synaptophysin, and negative for S-100 protein, α-smooth muscle actin, vimentin, glucagon, insulin, somatostatin, carcinoembryonic antigen, serotonin, and parathyroid hormone-related protein. Considering the distribution of chromogranin A-positive cells within the anal sac apocrine glands, this tumor was diagnosed as neuroendocrine carcinoma originating from the apocrine glands of the anal sac.

A case of hepatic carcinoid in a red deer hind (Cervus elaphus)

A carcinoid tumour in the liver of a red deer hind (Cervus elaphus) is described. Macroscopically, the liver was considerably enlarged with multifocal, firm, yellow and red nodular neoplastic masses, which were histopathologically diagnosed as hepatic carcinoids. The diagnosis was confirmed by modified Grimelius staining, which demonstrated numerous small argyrophilic granules in the cytoplasm of neoplastic cells, and by immunohistochemistry. The neoplastic cells gave a strong positive reaction for neuron-specific enolase (NSE) and synaptophysin and a weak positive reaction for chromogranin A. To our knowledge, this is the first report of a hepatic carcinoid in red deer.

Nasal tumor with widespread cutaneous metastases in a Golden Retriever

An intact, 8-year-old, male Golden Retriever dog was presented for evaluation of a nasal mass and approximately 30 firm, raised, variably ulcerated dermal and subcutaneous masses. Histopathology of both nasal and multiple skin masses revealed multiple nonencapsulated, infiltrative masses comprising clusters, anastomosing trabeculae, and packets of neoplastic, round to ovoid, hyperchromatic cells with marked nuclear molding. Surrounding the neoplastic cells was a marked stromal response in which many of the spindle-shaped cells expressed muscle-specific actin and had ultrastructural features consistent with myofibroblasts. A literature search indicates that this is the first report in a peer-reviewed journal of cutaneous metastasis of a nasal neuroendocrine tumor in any domestic animal species.

A neuroendocrine carcinoma of undetermined origin in a dog

In this report, we describe a case of neuroendocrine carcinoma of undetermined origin in a dog. Necropsy revealed scattered small neoplastic nodules in the bilateral lungs and a small nodule in the parapancreatic lymph node. Histopathologically, both pulmonary and lymph nodal nodules showed a similar histologic pattern, with neoplastic cells being arranged in diffusely proliferating sheet-like cellular nests separated by variable amounts of fibrous septa, sometimes forming rosettes and duct-like structures. Scattered small necrotic foci and invasion to fibrous septa were typically observed. Neoplastic cells showed round to oval-shaped nuclei with prominent nucleoli and abundant eosinophilic cytoplasm that were positive for Grimelius' silver impregnation staining and immunostaining with cytokeratin, synaptophysin, vasoactive intestinal peptide and chromogranin A, indicative of the development of a neuroendocrine carcinoma. However, judging from the distribution of tumors lacking the portion suggestive of the primary site in any organ examined, as well as no further indication of differentiation potential of neoplastic cells, this tumor has so far been diagnosed as neuroendocrine carcinoma of undetermined origin.

Nasal neuroendocrine carcinoma in a free-living Japanese raccoon dog (Nyctereutes procyonoides viverrinus)

Neuroendocrine carcinoma was diagnosed in the left nasal cavity of a free-living Japanese raccoon dog (Nyctereutes procyonoides viverrinus). Microscopically, the tumour consisted of sheets of anaplastic cells separated by narrow zones of fibrovascular stroma. The neoplastic cells had varying numbers of cytoplasmic granules stained by the Grimelius method. Immunohistochemically, the neoplastic cells were variably labelled for cytokeratin AE1/AE3, vimentin, chromogranin A and S-100. Ultrastructurally, some of the neoplastic cells had cytoplasmic membrane-bound dense-core granules of approximate diameter 140-240nm. The tumour had infiltrated the cerebrum and metastasized to the pituitary gland, mandibular and pulmonary lymph nodes, lungs, thyroid gland and adrenal glands.

Nasal and paranasal adenocarcinomas with neuroendocrine differentiation in dogs

Tumors of the nasal cavity or paranasal sinuses of 18 dogs were examined histopathologically, immunohistochemically, and histochemically. The tumors were classified histologically as 13 adenocarcinomas, 3 transitional carcinomas, 1 squamous cell carcinoma, and 1 adenosquamous carcinoma. Tumor cells were strongly immunoreactive for broad-spectrum cytokeratins in all cases, for cytokeratin 8/18 in 16 cases, and for cytokeratin 19 in 17 cases. None of the 18 carcinomas had cytologic or histologic features indicative of neuroendocrine differentiation, yet tumor cells in 5 of the 13 adenocarcinomas were argyrophilic and immunohistochemically positive for synaptophysin and chromogranin A. Results of this study indicate that neuroendocrine markers may be detected immunohistochemically and histochemically in canine nasal or paranasal adenocarcinomas despite the lack of typical histologic features of neuroendocrine differentiation.

Imaging Features and Decision Making in Retrobulbar Neuroendocrine Tumours in Horses ? Case Report and Review of Literature

A 25-year-old Haflinger gelding was evaluated for chronic-progressive unilateral exophthalmos. Ultrasonographic investigation and magnetic resonance (MR) imaging revealed a retrobulbar space-occupying mass to be the cause of eyeball displacement. Ultrasonographic features were not sufficient to specify the type and extension of the lesion. Magnetic resonance scans, however, clearly displayed an infiltrative intracranial growth pattern but sparing of orbital soft tissues. Based on MR appearance, tentative diagnosis of an orbital soft tissue neoplasia was made and subsequently confirmed by histopathological investigation. The latter revealed a poorly differentiated neuroendocrine tumour. Retrospectively, MR changes resembled those seen with neuroendocrine neoplasms of the human skull. Even if histopathology remains to be elucidated by cytological or histological inspection, MR imaging of equine orbital tumours should provide the criteria necessary for evaluating the therapeutic options and associated prognosis.

A thymic carcinoid in a Bengal tiger (Panthera tigris)

An 18-yr-old Bengal tiger (Panthera tigris) presented with acute onset hind limb paresis. Radiographic and ultrasonographic imaging revealed a caudal abdominal aortic thrombus and a cranial mediastinal mass. Necropsy confirmed aortic thrombosis. Necrotizing enteritis and multifocal renal thrombosis were also noted. The cranial mediastinum contained a bilobed mass that histologically and ultrastructurally was consistent with a carcinoid.

Neuroendocrine carcinoma in the nasal cavity of ten dogs

Neuroendocrine (NE) carcinoma was diagnosed in 10 dogs. In six cases examined by cephalometric radiography and computerized tomography, a large mass was seen to fill the nasal cavity. Histopathologically, sheets, nests or ribbons of neoplastic cells were separated by delicate or thick fibrovascular stroma. The neoplastic cells were round, oval, or spindle-shaped; cytoplasmic granules and hyperchromatic nuclei with prominent nucleoli were present. Neoplastic cells were invariably immunohistochemically positive for cytokeratin (CK) AE1/AE3, neuron-specific enolase, chromogranin A and vasoactive intestinal polypeptide. Eight dogs were positive for S100 protein, seven for synaptophysin, five for protein gene product 9.5, two for somatostatin, and one for Leu-7. Immunolabelling gave negative results for CK 8, CK 19, calcitonin, calcitonin gene-related polypeptide, neurofilaments, serotonin, gastrin and glial fibrillary acidic protein. Ultrastructurally, the neoplastic cells contained a large number of round, membrane-bounded, densely-cored granules corresponding to neurosecretory granules. These observations were consistent with the neuroendocrine nature of the carcinomas.

Nasal adenocarcinoma with diffuse metastases involving the orbit, cerebrum, and multiple cranial nerves in a horse

A 9-year-old Trakehner gelding was examined because of right exophthalmus. Clinical findings included a lack of menace response in the right eye, reduced direct and consensual right pupillary light reflexes, ventrolateral strabismus of the right eye, mild right-sided facial asymmetry, a head tilt to the left, and increased extensor tone in the right limbs. Findings were suggestive of a multifocal lesion affecting the right forebrain; right optic, oculomotor, and facial nerves; and left vestibulocochlear nerve. Ultrasonographic examination of the right eye revealed a vascular retrobulbar mass. Computed tomographic imaging revealed a mass that filled the nasal cavity and invaded the forebrain. Necropsy revealed an undifferentiated nasal adenocarcinoma affecting the orbit with metastases to the right parotid gland, cranial cervical lymph nodes, fascial planes of the neck, and lungs. No evidence of direct involvement of the right facial and left vestibulocochlear nerves was found, suggesting the possibility of paraneoplastic peripheral neuropathy.

A carcinoid tumor in the gallbladder of a dog

A cholecystectomy was performed on a 10-year-old spayed female mixed-breed dog with chronic weight loss, persistently increased liver enzyme activities, and cholecystomegaly identified by ultrasonographic examination. A subsequent diagnosis of a biliary carcinoid was made based on a neuroendocrine-type histologic pattern, cytoplasmic argyrophilia by Grimelius staining, immunopositivity for chromogranin A, and the ultrastructural finding of cytoplasmic secretory granules in neoplastic cells. Extrahepatic biliary carcinoid tumors are rare tumors of humans and have not been documented in domestic animals.

Computed tomography and magnetic resonance imaging of the equine head

Horses are frequently presented with clinical conditions warranting diagnostic imaging of the head. Unfortunately, evaluation of the equine head can be difficult using conventional radiography. The anatomic complexity and superimposition of the osseous, dental, and soft tissue structures complicate radiographic interpretation and diagnoses. Multiple radiographic projections may be necessary to image specific regions, and side-to-side comparison is often essential.