Histological, histochemical and immunohistochemical study of the haemal nodes of the dromedary camel

Haemal nodes are lymphoid organs found in various mammals and some birds. The structure of haemal nodes has been described in a number of species but not yet in the camel. Therefore, haemal nodes from 10 camels were studied histologically and tested for CD3, CD22, major histocompatibility complex (MHC) class II/DR, alpha-smooth muscle actin and for the demonstration of acid and alkaline phosphatases. The haemal nodes were of spherical or kidney shape with one or two hili and had a capsule and trabeculae of connective tissue and smooth muscles. The main parenchyma was composed of a cortex and a medulla. The cortex was formed from lymphoid follicles and diffuse interfollicular lymphocytes. The medulla consisted of lymphoid cords separated by medullary sinuses. The interfollicular lymphocytes and those in the medullary cord were CD3-positive. The lymphoid follicles showed CD22-positive cells. MHC class II/DR was expressed by most cells of the parenchyma. There were also subcapsular, peritrabecular and medullary blood sinuses. Afferent and efferent lymphatics and lymphatic sinuses were also found. Acid phosphatase-positive cells were localized mainly in the marginal, the interfollicular zone and in the medullary cord. Alkaline phosphatase positivity was observed in the endothelium of the sinuses and in the lymphoid follicles. The morphology of these organs in the camel allows a classification as haemolymph nodes and suggests involvement in blood and lymph filtration.     

Splenic marginal zone lymphoma in 5 dogs (2001-2008)

Background: Splenic marginal zone lymphomas (MZL) in dogs arise from the marginal zone of B‐cell follicles and can progress slowly. Objectives: To describe clinical features, treatment, and outcome of dogs with splenic MZL. Animals: Five dogs with naturally occurring MZL. Methods: Clinical, laboratory, and follow‐up data were retrospectively reviewed. Diagnosis was based on clinical, histopathological, and immunophenotypic features. Results: All dogs had stage IV disease; among them, 2 were symptomatic (substage “b”) because of splenic rupture. Four dogs underwent splenectomy and adjuvant doxorubicin, and 1 dog underwent surgery only. Three out of the 4 dogs treated with surgery and chemotherapy died of causes unrelated to lymphoma, after 760, 939, and 1,825 days, whereas the remaining dog was alive and in complete remission after 445 days. The dog not receiving any adjuvant treatment had recurrence of the tumor after 180 days. Conclusions and Clinical Importance: Splenic MZL appears indolent and can benefit from splenectomy, with or without systemic chemotherapy.     

Characterization of membranous (M) cells in normal feline conjunctiva-associated lymphoid tissue (CALT)

Objective To characterize conjunctival lymphoid nodules obtained from the nictitans of healthy cats to determine if the follicle‐associated epithelium (FAE) of conjunctiva‐associated lymphoid tissue (CALT) in this species contains membranous (M)‐cells analogous to those described in other regions of mucosa‐associated lymphoid tissue (MALT). Methods Lymphoid follicles from nictitan bulbar surfaces of 10 healthy cats (20 eyes total) were examined. Nictitans from five cats were harvested immediately post‐mortem and a minimum of 12 lymphoid nodules from each third eyelid were isolated using a Zeiss operating microscope. At least three lymphoid follicles from each eye were examined using light microscopy (LM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) using standard fixation and embedding protocols. Nictitan‐lymphoid follicles from another five healthy cats were processed for immunohistochemistry to characterize the distribution of T‐ and B‐lymphocytes present beneath the FAE. Results The FAE overlying CALT from 10 healthy cats demonstrated morphology characteristic of M‐cells including attenuated apical cell surface with blunted microvilli and microfolds, invaginated basolateral membrane forming a cytoplasmic pocket, and diminished distance between the apical and pocket membrane. Immunohistochemistry of lymphoid tissue subtending the FAE demonstrated B‐cell dependent regions in the germinal centers surrounded by T‐cell dependent interfollicular zones. Conclusions Healthy feline CALT contains morphologic features analogous to those described in other regions of MALT. Documentation of feline conjunctival M‐cells is of clinical relevance in the study of primary infectious, allergic, and autoimmune ocular diseases, as well as a potential means of vaccination or drug delivery.     

Primary lymphoma of the uterine horn in a Lhasa Apso dog

Primary lymphomas of the canine female genital tract are uncommon tumours. A 9-year-old intact female Lhasa Apso dog presenting with a closed pyometra underwent an ovariohysterectomy (OHE), and the hyperplastic uterine horn along with multiple follicular cysts on the right ovary was examined by histological analysis. Severe infiltration of medium-sized lymphocytes with strong positive immunoreactivity for CD79a and numerous anaplastic features was detected in the unilateral uterine horn, and the dog was diagnosed as having extranodal marginal zone B-cell lymphoma (MZBCL). The present case reports an extremely rare occurrence of primary lymphoma involving the uterine horn in a dog and describes histological characteristics of the tumour for definite diagnosis.     

Hemangiosarcoma of the third eyelid in a dog

Abstract A case of hemangiosarcoma of the third eyelid in a 7-year-old Caucasian Sheepdog is reported. A voluminous red mass protruding from the free edge of the third eyelid in the right eye was present. The mass and the free edge of the third eyelid were surgically excised. On histopathologic examination the tumor was seen to infiltrate the propria of the third eyelid and was composed of neoplastic mesenchymal cells forming irregular channels containing blood. These plump cells showed moderate anisocytosis and anisokaryosis with a low mitotic index. The surgical wound healed successfully and after 9 months there had been no recurrence. To the authors' knowledge, this is the first hemangiosarcoma of the third eyelid reported in the dog.     

Histological, histochemical and immunohistochemical study of the lymph nodes of the one humped camel (Camelus dromedarius)

Prescapular, femoral, mesenteric, mediastinal and splenic lymph nodes from nine camels of one to 12 years of age were studied. There were no obvious structural differences between these different lymph nodes or between the ages. The lymph nodes were surrounded by a capsule formed of two layers, an outer thicker layer of connective tissue and an inner thinner layer mainly of smooth muscles. Trabeculae extended from the inner layer of the capsule dividing the parenchyma characteristically into incomplete lobules. Subcapsular and trabecular lymphatic sinuses were supported by a reticular fiber network. The parenchyma was uniquely different from that of other species, as it was arranged in the form of lymphoid follicles and interfollicular lymphoid tissue. The lymphoid follicles of CD22 positive lymphocytes were supported by a reticular fiber network. This fine network of α-smooth muscle actin positive cells enclosed the lymphoid follicles. The interfollicular tissue was mainly made up of diffusely distributed CD3 positive lymphocytes. MHC class II: DR was expressed by most lymphocytes of the follicles and interfollicular tissue. Lymphatic sinuses and high endothelial venules were found in the interfollicular zone. The lymphatic sinuses were lined by discontinuous endothelial cells. The wall of the high endothelial venules was infiltrated by several lymphocytes and enclosed in a layer of α-smooth muscle actin positive cells. Acid phosphatase positive cells were evenly distributed in the interfollicular zone. A few cells were localized in the lymph follicles. Alkaline phosphatase was observed in the endothelium of the lymphatic sinuses and in the lymphoid follicles.     

Progression of an orbital T-cell rich B-cell lymphoma to a B-cell lymphoma in a dog

An 11-year-old Shetland Sheepdog was presented for exophthalmos caused by a locally extensive, poorly defined mass located behind the right eye. The primary orbital mass was identified by light microscopy and immunohistochemistry as a T-cell rich B-cell lymphoma (TCRBCL) composed predominantly of BLA.36-positive large neoplastic lymphoid cells admixed with fewer CD3- and CD79a-positive small lymphocytes. The dog was treated for lymphoma, but 6 months after presentation it was euthanatized for suspected hepatic and gastrointestinal metastasis. Gross findings revealed an enlarged liver with multiple well-demarcated, randomly distributed 0.1-1.5-cm white nodules, five firm white submucosal jejunal nodules, and ileocecal, mediastinal, and hilar lymphadenopathy. Metastatic liver lesions consisted of sheets of monomorphic large neoplastic lymphoid cells that effaced and expanded portal and centrilobular zones. These cells were morphologically similar to the large neoplastic cells of the original orbital tumor and were CD3-negative and variably BLA.36-positive, consistent with B-cell lineage. Similar cells comprised the jejunal nodules and effaced the lymph nodes. The progression of TCRBCL to a diffuse B-cell lymphoma in this case is consistent with reported human cases and has not been previously reported in the dog.     

Unicentric extranodal lymphoma of the upper eyelid conjunctiva in a dog

A case of conjunctival lymphoma in a 4-year-old Siberian husky is reported. A large red mass protruding from the conjunctiva of the upper eyelid of the right eye was present. Irritation, blepharospasm and epiphora were revealed on initial ophthalmic examination. After anti-inflammatory treatment, surgery was performed. Histologically, the mass consisted of large polygonal cells with a high nucleus to cytoplasm ratio, moderate amounts of slightly eosinophilic cytoplasm, pleomorphic nuclei with vesicular chromatin and prominent multiple nucleoli. Mitotic figures were frequent. Approximately 70% of the neoplastic cells were CD3 positive and CD79alpha negative. On the basis of histologic and immunohistochemical findings, a diagnosis of intermediate-grade, diffuse large-cell lymphoma with T-cell immunophenotype was made. The surgical area healed uneventfully and, although chemotherapy was not received, after 12 months the dog exhibited no recurrence. To the authors' knowledge, this is the first report of unicentric extranodal conjunctival lymphoma in a dog.     

Bilateral third eyelid ectopic cilia in an adult horse

A 15‐year‐old Cob mare presented with a 4‐month history of chronic epiphora and intermittent blepharospasm in the right eye. On ophthalmic examination, two translucent aberrant hairs were identified at the third eyelid margin corresponding to an area of corneal fibrosis and neovascularization. Partial excision of the third eyelid was performed, and histopathology confirmed ectopic hair follicles. Two weeks later, clinical signs recurred in the same eye. Examination revealed another pair of aberrant hairs on the bulbar surface of the third eyelid near its leading edge. This portion of the third eyelid was also excised, and histopathology confirmed two additional ectopic hair follicles. Eight months later, the horse developed similar clinical signs in the left eye. Ophthalmic examination showed a single aberrant translucent hair at the third eyelid margin associated with focal fibrosis and neovascularization of the ventromedial cornea. Partial excision of the third eyelid was performed, and histopathology confirmed an ectopic hair follicle within the third eyelid conjunctiva. Excision was curative at 4 years postoperatively with no further recurrence in either eye.     

Evaluation of peripheral lymphoreticular biopsy techniques and their clinical side effects in sheep

Tissue samples were collected postmortem from 126 sheep at five lymphoreticular sites by different techniques. The three most successful combinations of sites and techniques were: the third eyelids, using a forceps and scissors, which provided a mean (se) of 5.32 (0.70) lymphoid follicles per 5 microm tissue section, a mandibular lymph node, using a Biopty gun, which gave 1.19 (0.26) lymphoid follicles per 5 microm tissue section, and tonsil, using a biopsy forceps, which gave 1.14 (0.27) lymphoid follicles per 5 microm tissue section. These three techniques were repeated once a month for five months on five sheep under general anaesthesia, and their clinical effects were compared with five control sheep which were restrained and anaesthetised in the same way but from which no biopsies were taken. Most lymphoid follicles (3.47 [0.58] per 5 pm tissue section) were obtained by using the third eyelid biopsy technique. There were no clinical side effects associated with the biopsy procedure. There were increases in the plasma concentration of cortisol in all the animals, suggesting that the restraint and anaesthesia were more stressful than the biopsy procedure.     

Extraocular muscle dysinnervation disorder resembling Duane retraction syndrome in a 9‐month‐old French Bulldog

A 9‐month‐old French Bulldog was presented with a chronic history of lateral strabismus and intermittent third eyelid protrusion in the left eye. The neuro‐ophthalmological examination revealed mild ptosis of the left upper eyelid, mild lateral strabismus, and external ophthalmoparesis of the left eye. Retraction and ventral deviation of the left eye globe with protrusion of the third eyelid and elevation of the upper eyelid were elicited on attempted voluntary adduction of the left eye. Hematology, serum biochemistry, serology for infectious diseases, magnetic resonance of the head, and cerebrospinal fluid analysis did not reveal significant abnormalities. Forced duction test did not show signs of mechanical restriction in ocular motility. A suspected congenital cranial dysinnervation disorder resembling Duane retraction syndrome in humans was diagnosed based on the typical clinical signs and exclusion of structural abnormalities. The clinical signs remained stable for 9 months until the time of writing this report.     

Precursor B-1 B cell lymphoma in a newborn calf.

A newborn Holstein female calf had neoplastic lesions in the skin and within the thoracic and abdominal cavities but not in the bone marrow, spleen, thymus, or most lymph nodes. Because the tumor cells were positive for CD79a (B cell marker), CD5 (B-1 cell marker) and terminal deoxynucleotidyl transferase (marker for immature lymphoid precursors), a diagnosis of precursor B-1 B cell lymphoma was made. The diagnosis was strongly supported by the fact that B-1 cells can develop in the fetus, unlike B-2 cells, which are produced after birth. The lymphoma was distinct from the typical calf form of lymphoma of B-2 cell origin, which does not express CD5 and is characterized by generalized lymphadenopathy and involvement of the bone marrow, blood and spleen.     

Nasal and nasopharyngeal lymphoma in cats: 50 cases (1989-2005)

Lymphoma is the most common nasal cavity tumor in cats, yet few reports specifically address the anatomic, immunohistologic, and cytologic features of this neoplasm. Fifty cats were diagnosed with lymphoma at necropsy, via biopsy or by cytology alone. Ten cats displayed multiorgan involvement, and in 2 of these the involvement was limited to the cerebellum and frontal cortex, respectively. Of the tumors, 41 of 50 (82%) were classified as nasal lymphoma, 5 of 50 (10%) were classified as nasopharyngeal lymphoma, and 4 of 50 (8%) involved both nasal and nasopharyngeal tissue. Histologically, all were considered diffuse lymphoid neoplasms and no cats displayed features of follicular lymphoma. Of the 44 cases available for slide review by the pathologist, 40 of 44 (91%) were classified as immunoblastic lymphoma, 2 of 44 (5%) as diffuse large cell, and 1 as diffuse mixed; 1 was unclassified. Of the 45 cats for which immunohistochemical stains were available, 32 were uniformly positive for CD79a, 7 were uniformly CD3 positive, and 6 had a mixed population of CD79a and CD3 cells. Epithelioptropism was exhibited in 4 of 5 (80%) cats in which there was sufficient epithelium present for evaluation. Of those 4, 3 were B-cell and 1 was a granulated T-cell lymphoma. In the 21 cats which nasal cytology was performed, 15 were cytologically diagnosed with lymphoma; the diagnoses in the remaining five cats were inflammatory (n = 4), normal lymphoid tissue (n = 1), or nondiagnostic (n = 1). The most common biochemical abnormalities were panhyperproteinemia in 26/46 (57%) of cats and hypocholesterolemia in 11/46 (24%) of cats.     

Everted third eyelid cartilage in a cat: a case report and literature review

An 8-year-old neutered female British Blue cat was presented with a presumed diagnosis of a prolapsed nictitans gland and associated ocular irritation and epiphora. However, during surgery, the apparent nictitans gland protrusion was determined to be an everted cartilage of the nictitating membrane. The scrolled portion of the cartilage was removed through an incision through the conjunctiva on the bulbar aspect of the third eyelid, as previously described in the dog. This operation resolved the ocular irritation occurring, and the third eyelid returned to its anatomically correct position.     

Malignant lymphoma in nasal cavity and paranasal sinuses of a dog

A case of a canine large cell type T-cell lymphoma, with features of high-grade malignancy is described. The tumour was found confined in the nasal cavity and the paranasal sinuses of a crossbred German Shepherd dog. Histological examination revealed the features of a highly malignant large cell lymphoma. Ultrastructurally, the lymphoid tumour cells bore cytoplasmic protrusions that interdigitated tightly. From a panel of tumour markers used, the neoplastic cells were stained only for vimentin. Immunophenotyping of the tumour cells by means of CD3, CD79, kappa-light chains and lambda-light chains detection was undertaken. The tumour stained only for CD3 and was classified as T-cell lymphoma.     

Use of a sclerosing agent (1% polidocanol) to treat an orbital mucocele in a dog

A case of a salivary gland mucocele in a dog causing nonpainful exopthalmos with dorsolateral deviation of the globe and protrusion of the third eyelid. Diagnosis was made via ultrasound and confirmed with computed tomography. Aspiration of the cystic material along with injection of a sclerosing agent, 1% polidocanol (Aethoxysklerol), was used to destroy the mucocele. Follow-up monthly examination post injection confirmed resolution of clinical signs to date, namely abnormal globe position, with no complications observed.     

B‐cell lymphoma with plasmacytoid differentiation,atypical cytoplasmic inclusions,and secondary leukemia in a dog

A 7‐year‐old male castrated Jack Russell Terrier was presented to the oncology service at the University of California–Davis Veterinary Medical Teaching Hospital for evaluation of suspected lymphoma. The dog had several enlarged lymph nodes and moderate lymphocytosis. Aspirates of an enlarged inguinal lymph node contained a bimorphic population of large immature lymphocytes and smaller cells with plasmacytoid features. Both cell types often contained a single large cytoplasmic inclusion that varied from clear to pale pink to sky blue. Cytologic changes were interpreted as most consistent with lymphoid neoplasia. Based on the predominantly mature cell morphology and some morphologic heterogeneity, the peripheral lymphocytosis was interpreted as most likely reactive in nature. However, the immunophenotype of the cells (CD20+, CD21+, CD79a+, MUM‐1+, and MHCII+) and clonality assays showed that tissue and blood lymphocytes were neoplastic B cells with clonal identity despite their different morphologic appearances. The cytoplasmic inclusions were positive with periodic acid‐Schiff and were immunoreactive for IgM and IgG. By transmission electron microscopy, inclusions consisted of aberrant rough endoplasmic reticulum; a few small Russell bodies were also noted. A final diagnosis of high‐grade B‐cell lymphoma with plasmacytoid differentiation, atypical cytoplasmic inclusions, and secondary leukemia was made. Chemotherapy was initiated, but the dog was euthanized due to severe and uncontrolled seizures 9 months after the initial diagnosis. This case extends the morphologic repertoire of canine plasmacytoid neoplasms and emphasizes their continuum with multicentric lymphoma. This case also demonstrates the need for advanced diagnostic techniques in establishing blood involvement in lymphoma in some instances.     

Canine nodal marginal zone lymphoma: Descriptive insight into the biological behaviour

Canine nodal marginal zone lymphoma (nMZL) is classified as an indolent lymphoma. Such lymphomas are typified by low mitotic rate and slow clinical progression. While the clinical behaviour of canine splenic MZL has been described, characterized by an indolent course and a good prognosis following splenectomy, there are no studies specifically describing nMZL. The aim of this study was to describe the clinical features of and outcome for canine nMZL. Dogs with histologically confirmed nMZL undergoing a complete staging work‐up (including blood analysis, flow cytometry [FC] on lymph node [LN], peripheral blood and bone marrow, imaging, histology and immunohistochemistry on a surgically removed peripheral LN) were retrospectively enrolled. Treatment consisted of chemotherapy or chemo‐immunotherapy. Endpoints were response rate (RR), time to progression (TTP) and lymphoma‐specific survival (LSS). A total of 35 cases were enrolled. At diagnosis, all dogs showed generalized lymphadenopathy. One‐third was systemically unwell. All dogs had stage V disease; one‐third also had extranodal involvement. The LN population was mainly composed of medium‐sized CD21+ cells with scant resident normal lymphocytes. Histology revealed diffuse LN involvement, referring to “late‐stage” MZL. Median TTP and LSS were 149 and 259 days, respectively. Increased LDH activity and substage b were significantly associated with a shorter LSS. Dogs with nMZL may show generalized lymphadenopathy and an advanced disease stage. Overall, the outcome is poor, despite the “indolent” designation. The best treatment option still needs to be defined.     

Topical hypertonic saline as a treatment for ocular and nasal hirudiniasis in a dog

This case report describes ocular and nasal leech infestation (hirudiniasis) in a dog. The patient presented for a suspected ocular foreign body. The patient was sedated to allow proper examination, which revealed a leech foreign body attached to the bulbar conjunctiva adjacent to the inferotemporal limbus of the left eye. A 3.5% hypertonic saline solution was applied topically to the eye in four sequential drops, until the leech detached itself and was removed with a cotton bud. The affected eye was found to have a small corneal ulcer, a small area of scleral haemorrhage, and prominent lymphoid follicles within the third eyelid. Approximately 5 min after the leech was removed, another leech emerged from the left nostril. The patient was sent home on chloramphenicol ointment for treatment of the corneal ulcer, was rechecked 4 days later by an American Board of Veterinary Ophthalmology resident (PM) and found to have a normal ocular exam. This case report highlights that topical hypertonic saline solution (3.5%) can be an effective and easily prepared treatment for ocular and nasal hirudiniasis in veterinary patients.