Sensitivity and specificity of methods of assessing the regional lymph nodes for evidence of metastasis in dogs and cats with solid tumors

OBJECTIVE: To determine sensitivity and specificity of physical examination, fine-needle aspiration, and needle core biopsy of the regional lymph nodes for evidence of metastasis in dogs and cats with solid tumors. DESIGN: Case series. ANIMALS: 37 dogs and 7 cats. PROCEDURE: Regional lymph nodes were evaluated by means of physical examination (palpation), fine-needle aspiration, and needle core biopsy. Results were compared with results of histologic examination of the entire lymph node, the current standard. RESULTS: Tumors included 18 sarcomas, 16 carcinomas, 7 mast cell tumors, and 3 other tumors. Carcinomas were more likely to have metastasized to the regional lymph node (7/16 animals) than were sarcomas (2/18). Sensitivity and specificity of physical examination were 60 and 72%, respectively. Sensitivity and specificity of cytologic examination of fine-needle aspirates were 100 and 96%, respectively. Sensitivity and specificity of histologic examination of needle core biopsy specimens were 64 and 96%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that fine-needle aspiration may be a sensitive and specific method of evaluating the regional lymph nodes in dogs and cats with solid tumors, because results correlated well with results of histologic examination of the entire lymph node. Physical examination alone was not a reliable method and should not be used to decide whether to aspirate or biopsy the regional lymph nodes.     

Inflammatory myopathies.

Inflammatory myopathies are the result of infiltration of inflammatory cells into striated muscle, with or without an association with an underlying cause. Two broad classifications are IIMs and secondary inflammatory myopathies associated with other diseases. Standard diagnostic criteria for inflammatory myopathy include the presence of weakness or loss of specific muscle group function, an increase in CK, EMG changes associated with muscle membrane instability, and histologic evidence of inflammation. Not all these criteria, however, must be present. Fresh-frozen biopsy from two proximal muscles is recommended for biopsy confirmation. IIM can either focally affect head or neck muscles or be more diffuse. MMM is an immune-mediated disease characterized by a humoral antibody produced against the unique type IIM and type I variant mvofibers of masticatory muscles of dogs, which causes inflammation and loss of function of the muscles of mastication. Idiopathic polymyositis can affect focal muscle groups (extraocular, laryngeal) or present as multifocal or diffuse involvement of skeletal muscle in the cat and dog. Familial canine DM is an inflammatory disease of the striated muscle, skin, and vasculature in young Collies, Shetland Sheepdogs (Shelties), and, rarely, Collie-crossbred dogs. Immunosuppressive therapy is the key to successful treatment. Protozoal parasitic myopathies are the most common cause of clinically relevant secondary inflammatory myopathies. The degree of systemic involvement is often the limiting factor to successful treatment. Early recognition of the clinical signs for proper diagnostic testing and institution of appropriate therapy can result in a rewarding outcome in treating inflammatory myopathies in the cat and dog.     

FEASIBILITY OF CONTRAST‐ENHANCED ULTRASOUND‐GUIDED BIOPSY OF SENTINEL LYMPH NODES IN DOGS

Our goal was to develop and validate a technique to identify the sentinel lymph nodes of the mammary glands of healthy dogs with contrast‐enhanced ultrasound, and evaluate the feasibility of obtaining representative samples of a sentinel lymph node under ultrasound guidance using a new biopsy device. Three healthy intact female adult hounds were anesthetized and each received an injection of octafluoropropane‐filled lipid microspheres and a separate subcutaneous injection of methylene blue dye around a mammary gland. Ultrasound was then used to follow the contrast agent through the lymphatic channel to the sentinel lymph node. Lymph node biopsy was performed under ultrasound guidance, followed by an excisional biopsy of the lymph nodes and a regional mastectomy procedure. Excised tissues were submitted for histopathologic examination and evaluated as to whether they were representative of the node. The ultrasound contrast agent was easily visualized with ultrasound leading up to the sentinel lymph nodes. Eight normal lymph nodes (two inguinal, one axillary in two dogs; two inguinal in one dog) were identified and biopsied. Lymphoid tissue was obtained from all biopsy specimens. Samples from four of eight lymph nodes contained both cortical and medullary lymphoid tissue. Contrast‐enhanced ultrasound can be successfully used to image and guide minimally invasive biopsy of the normal sentinel lymph nodes draining the mammary glands in healthy dogs. Further work is needed to evaluate whether this technique may be applicable in patients with breast cancer or other conditions warranting evaluation of sentinel lymph nodes in animals.     

Extracutaneous mast-cell tumor in the dog

Three neoplasms of extracutaneous mast-cell origin, arising from the nasopharynx, oral cavity, and hepatopancreatic lymph nodes respectively, were diagnosed in three dogs. The neoplasms had histologic features similar to those of cutaneous mast-cell tumors, but had limited metastasis mostly involving the regional lymph nodes. One dog had a perforating duodenal ulcer, suggesting that duodenal ulcers can occur with extracutaneous tumors as they do with some cutaneous mast-cell tumors in the dog.     

Detection of Bartonella henselae DNA in two dogs with pyogranulomatous lymphadenitis

CASE DESCRIPTION: 1 dog evaluated because of inappetence and lameness of the left hind limb of 1 day's duration and 1 dog evaluated because of inappetence, fever, and lymphadenopathy of 2 weeks' duration. CLINICAL FINDINGS: Histologic examination of excisional biopsy specimens from lymph nodes revealed pyogranulomatous lymphadenitis in both dogs. Quantitative real-time PCR assays detected Bartonella henselae DNA in blood samples and affected lymph node specimens from both dogs. Antibodies against B. henselae were not detected via immunofluorescent antibody testing during active disease in either dog. TREATMENT AND OUTCOME: 1 dog recovered after 6 weeks of treatment with doxycycline (5 mg/kg [2.3 mg/lb], p.o., q 12 h), whereas the other dog recovered after receiving a combination of azithromycin (14.5 mg/kg [6.6 mg/lb], p.o., q 24 h for 21 days), doxycycline (17.3 mg/kg [7.9 mg/lb], p.o., q 24 h for 4 weeks), and immunosuppressive corticosteroid (prednisone [3 mg/kg {1.4 mg/lb}, p.o., q 24 h], tapered by decreasing the daily dose by 25% every 2 weeks) treatment. CLINICAL RELEVANCE: B. henselae is implicated as a possible cause or a cofactor in the development of pyogranulomatous lymphadenitis in dogs. In dogs with pyogranulomatous lymphadenitis, immunofluorescent assays may not detect antibodies against B. henselae. Molecular testing, including PCR assay of affected tissues, may provide an alternative diagnostic method for detection of B. henselae DNA in pyogranulomatous lymph nodes.     

Colonic lymphocyte and plasma cell populations in dogs with lymphocytic-plasmacytic colitis

OBJECTIVES: To quantitate immunoglobulin-containing cells (IgA, IgG, and IgM) and CD3+ T cells in colonic biopsy specimens obtained from dogs with lymphocytic-plasmacytic colitis (LPC), and to compare lymphocyte and plasma cell populations in dogs with LPC with those in healthy dogs. ANIMALS: 10 healthy dogs and 11 dogs with LPC. PROCEDURE: Colonic mucosal specimens obtained from healthy dogs and dogs with LPC were stained specifically for IgA-, IgG-, and IgM-containing cells and CD3+ T cells by use of immunoperoxidase techniques. Morphometric analyses were done to quantitate lymphocytes and plasma cells in standardized areas of colonic mucosa. Data analyses allowed determination of mean cell numbers in each dog group, and comparison of mean numbers of lymphocytes and plasma cells between dog groups. RESULTS: CD3+ T cells predominated in healthy dogs, whereas CD3+ T cells and IgA-containing cells were most numerous in dogs with LPC. In both dog groups, the IgG- and IgM-containing cells were considerably less numerous than the other 2 cell types. Comparison of cell populations between dog groups indicated that IgA- and IgG-containing cells and CD3+ T cells were significantly more numerous in the colonic mucosa of dogs with LPC. CONCLUSIONS: Dogs with LPC have significantly increased numbers of IgA- and IgG-containing cells and CD3+ T cells. These lymphocyte and plasma cell distributions indicate similarities to and differences from such distributions in human beings with inflammatory bowel disease. Results provide a basis for future correlation between histologic stage of disease activity and immunologic findings in dogs with LPC.     

Extraocular muscle myositis and restrictive strabismus in 10 dogs

Ten cases of uni- or bilateral restrictive ventromedial strabismus in young dogs of different breeds are reported. Clinically, abnormalities were restricted to the extraocular muscles with sparing of the masticatory muscles and limb muscles. This was supported in some cases by imaging studies, electrophysiology, and immunocytochemical assay for antibodies against type 2M fibers. Histologically, there was variable lymphocytic plasmacytic mononuclear cell infiltration and fibrosis. This disorder is similar in many aspects to chronic masticatory myositis with focal myositis and subsequent fibrosis. Surgical correction may restore eye position and vision.     

Histologic comparison of skin biopsy specimens collected by use of carbon dioxide or 810-nm diode lasers from dogs

OBJECTIVE: To compare histologic artifacts caused by carbon dioxide (CO2) or 810-nm diode surgical lasers used to obtain small biopsy specimens of skin from healthy dogs. DESIGN: Prospective study. ANIMALS: 4 dogs. PROCEDURE: 21 skin biopsy specimens were collected from each dog. Three biopsy specimens were obtained with a CO2 or an 810-nm diode laser at 3 operating settings each, and 3 biopsy specimens were obtained with a 6-mm biopsy punch instrument (controls). After processing, biopsy specimens were examined for artifacts related to laser-tissue interactions. Microscopically visible char was measured from the lateral edge of each specimen obtained with a laser. RESULTS: There were no significant differences among mean char distances in biopsy specimens obtained with the CO2 laser at various settings. Mean char distance was significantly greater in all skin biopsy specimens obtained with the diode laser, compared with those obtained with the CO2 laser. Mean char distance was significantly greater in biopsy specimens obtained with the 810-nm diode laser at high power, compared with biopsy specimens obtained with the 810-nm diode laser at low power. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the CO2 laser caused less thermal injury at margins of skin biopsy specimens; therefore, if a surgical laser is used for removal of cutaneous masses or to obtain skin biopsy specimens, use of the CO2 laser is recommended. Veterinarians performing a biopsy by using a surgical laser should be aware that laser-induced artifacts may render small biopsy specimens useless for providing accurate histologic diagnosis.     

Indirect magnetic resonance lymphography of the head and neck of dogs using Gadofluorine M and a conventional gadolinium contrast agent: A pilot study

The purpose of this pilot study was to evaluate lymph node enhancement with an indirect magnetic resonance (MR) lymphography technique using 2 different contrast agents in the head and neck region of healthy dogs. Five dogs were imaged at various times after intradermal injection of gadoversetamide and Gadofluorine M (minimum of 1 week apart) in the right and left mandibular, temporal, and lateral neck regions. We observed consistent progressive enhancement with time in the mandibular, retropharyngeal, and superficial cervical lymph nodes. The node enhancement was comparable for both contrast agents. Contrast enhancement of the parotid lymph nodes was not seen. We conclude that this technique of indirect MR lymphography using either agent could be used to identify those lymph nodes at highest risk of metastatic disease in dogs with cancer, and to guide staging and treatment.     

Repeated transplacental transmission of Neospora caninum in dogs

Four litters of German Shorthaired Pointers from one owner developed a toxoplasmosis-like illness. According to the records, 29 of 39 dogs had hind limb paralysis. Six dogs from 2 litters were necropsied and had generalized encephalomyelitis. Tachyzoites and tissue cysts of Neospora caninum were found in the brain and spinal cord of each dog. Lesions were found in the eyes, extraocular muscles, or both in all of the dogs, and N caninum was detected microscopically in the eyes (retina and choroid in 1 dog), extraocular muscles, or both in 5 of the 6 dogs. Ocular lesions consisted of focal retinitis, choroiditis, mild nonspecific iridocyclitis, and myositis of extraocular muscles. Organisms stained with anti-N caninum serum, but not with anti-Toxoplasma gondii serum in an immunohistochemical test, except in 1 dog. In one dog, aged thick-walled N caninum tissue cysts reacted mildly with anti-T gondii serum.     

Experimental induction of chronic borreliosis in adult dogs exposed to Borrelia burgdorferi-infected ticks and treated with dexamethasone.

OBJECTIVE: To develop a method to experimentally induce Borrelia burgdorferi infection in young adult dogs. ANIMALS: 22 healthy Beagles. PROCEDURE: All dogs were verified to be free of borreliosis. Twenty 6-month-old dogs were exposed to Borrelia burgdorferi-infected adult ticks and treated with dexamethasone for 5 consecutive days. Two dogs not exposed to ticks were treated with dexamethasone and served as negative-control dogs. Clinical signs, results of microbial culture and polymerase chain reaction (PCR) testing, immunologic responses, and gross and histologic lesions were evaluated 9 months after tick exposure. RESULTS: Predominant clinical signs were episodic pyrexia and lameness in 12 of 20 dogs. Infection with B burgdorferi was detected in microbial cultures of skin biopsy specimens and various tissues obtained during necropsy in 19 of 20 dogs and in all 20 dogs by use of a PCR assay. All 20 exposed dogs seroconverted and developed chronic nonsuppurative arthritis. Three dogs also developed mild focal meningitis, 1 dog developed mild focal encephalitis, and 18 dogs developed perineuritis or rare neuritis. Control dogs were seronegative, had negative results for microbial culture and PCR testing, and did not develop lesions. CONCLUSIONS AND CLINICAL RELEVANCE: Use of this technique successfully induced borreliosis in young dogs. Dogs with experimentally induced borreliosis may be useful in evaluating vaccines, chemotherapeutic agents, and the pathogenesis of borreliosis-induced arthritis.     

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF PRESUMED NORMAL CANINE ABDOMINAL LYMPH NODES

Though identification of lymph nodes is essential in staging cancer patients, little has been reported about the CT features of canine abdominal lymph nodes. The purpose of this retrospective study was to describe the visibility, location, and characteristics of abdominal lymph nodes in abdominal CT studies of dogs considered unlikely to have lymphadenopathy. The relationship between the number of identified lymph nodes and intraabdominal fat ranking, body weight, and slice thickness was also investigated. A total of 19 dogs were included. At least two jejunal lymph nodes and both left and right medial iliac lymph nodes were identified in all dogs. Colic lymph nodes were not identified in any of the dogs. Visualization of all other lymph nodes varied. There were significantly more lymph nodes visible in dogs with more intraabdominal fat (P < 0.0001). No correlation between the number of identified lymph nodes and body weight (P = 0.64) or slice thickness (P = 0.76) was found. Though most of all identified lymph nodes had an elongated shape, a rounded shape was most common in splenic, pancreaticoduodenal, renal, ileocolic and caudal mesenteric lymph nodes. Most lymph nodes had a homogeneous structure before and following the intravenous administration of contrast medium. Some lymph nodes had a slightly irregular structure or were relatively more hyper attenuating in the periphery than centrally before and/or after contrast administration. Mean attenuation before contrast was 37 Hounsfield Units (HU) (range 20–52 HU), and 109 HU after contrast (range 36–223 HU). Findings indicated that the CT visibility, characteristics of different abdominal lymph nodes may be variable in dogs.     

Association between lymph node size and metastasis in dogs with oral malignant melanoma: 100 cases (1987-2001)

OBJECTIVE: To determine the association between lymph node size and metastasis and to assess measurement of lymph node size as an accurate and reliable means of tumor staging in dogs with oral malignant melanoma. DESIGN: Retrospective study. ANIMALS: 100 dogs with histologically confirmed oral malignant melanoma. PROCEDURE: Clinical records for dogs with oral malignant melanoma were reviewed. Data regarding size and results of cytologic or histologic examination of lymph nodes were evaluated. The association between lymph node size and metastasis was determined. RESULTS: Forty-seven (47%) dogs, of which 23 (49%) had enlarged mandibular lymph nodes, had no cytologic or histologic evidence of metastasis. Of 53 (53%) dogs with cytologic or histologic evidence of mandibular lymph node metastasis, 37 (70%) had enlarged mandibular lymph nodes, and 16 (30%) had mandibular lymph nodes of normal size. Overall, 16 of the 40 (40%) dogs with normal-sized lymph nodes had microscopic evidence of metastatic disease. Sensitivity and specificity of lymph node size as a predictor of metastasis were 70 and 51%, respectively, and the positive and negative predictive values were 62 and 60%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Although a significant relationship was identified between lymph node size and metastasis to the lymph node, this association did not appear strong enough to be clinically relevant. Results suggest that lymph node size alone is insufficient for accurate clinical staging of oral malignant melanoma in dogs; cytologic or histologic examination of regional lymph nodes should routinely be performed, regardless of size of those nodes.     

ULTRASONOGRAPHIC EXAMINATION OF CERVICAL MASSES IN THE DOG AND CAT

The ultrasonographic appearance of clinically undifferentiated neck masses for which a definitive diagnosis was eventually obtained in nineteen dogs and one cat is presented in this report. Multiple lesions were seen ultrasonographically in 4 dogs and no cervical abnormalities were seen in 2 dogs resulting in 22 lesions in 20 annuals. Of 7 benign lesions, there were 2 patients with reactive lymph nodes from a regional inflammatory process, and 1 patient each with primary pyogranulomatous lymphadenitis, arteriovenous malformation, foreign body granuloma, cellulitis, and hematoma. Of 15 malignant lesions, 7 were thyroid carcinomas, 3 were lymphomas with submandibular and cervical lymph node enlargement, 3 were lymph node enlargements associated with regional metastasis of malignant tumors, one was a leiomyosarcoma and one was a carotid body tumor. One dog with a diffuse soft tissue swelling of the ventral cervical region had only slight asymmetry of the thyroid lobes on ultrasound examination and no abnormalities of the neck at post mortem. A second dog examined with ultrasound 4 months after surgical removal of a carotid body tumor had no evidence of tumor recurrence. Ultrasonographic examination provided information regarding the character of the lesions, the tissue or organ of origin, and invasion into other anatomic structures. Ultrasound examination in conjunction with fine needle or tissue biopsy provided a definitive diagnosis in those animals in which biopsies were performed.     

Use of the argyrophilic nucleolar region method for cytologic and histologic examination of the lymph nodes in dogs

Argyrophilic nucleolar organizer region (AgNOR) counts in cytologic and histologic lymph node samples from healthy dogs and dogs with lymphoma were compared. Control samples were taken from 10 Beagle dogs (six female and four male dogs, 1.5-2 years), and lymphoma samples were taken from 16 dogs. Cytologic samples were obtained by fine-needle aspiration and impression and histologic samples by excision or incisional biopsy. Altogether, 26 cytologic, 19 excisional, and 7 incisional biopsy samples were examined. Lymph nodes of controls showed a moderate inflammatory pattern; of the lymphoma cases, nine were low-grade forms and seven were high-grade forms. Mean AgNOR counts per nucleus were determined. AgNOR counts were statistically different (P < 0.001) between controls and lymphoma cases in cytologic (1.35 and 3.59, respectively) and histologic (1.4 and 2.89, respectively) samples. In lymphoma cases, AgNOR counts in cytologic samples were higher than those in histologic samples by 0.81 (P < 0.001) and showed a linear relationship (r = 0.6; P < 0.05) with the histologic counterparts in excisional biopsy samples. AgNOR counts in low- and high-grade lymphomas were significantly different (P < 0.05) in cytologic (3.21 and 4.08, respectively) and histologic (2.68 and 3.18, respectively) samples. In conclusion, AgNOR counts were higher in lymph nodes with lymphoma than in reactive nodes. In the case of dogs with lymphoma, AgNOR counts in cytologic samples were linearly related to excisional but not to incisional biopsy samples. Although AgNOR counts were different between cytologic and histologic samples, either sample type provided enough sensitivity to differentiate between high- and low-grade forms of lymphoma.     

Pythiosis of the digestive tract in dogs from Oklahoma

Enteric pythiosis was diagnosed in nine dogs in Oklahoma. Eight dogs had anorexia and weight loss. Two of these dogs had diarrhea; two dogs exhibited vomiting and diarrhea; and one dog had vomiting. One dog presented with dysphagia. Seven dogs had either a palpable or radiographically visible abdominal mass. These seven dogs had localized regions of mucosal ulceration and thickened gastric or intestinal walls with some involvement of the adjacent mesentery or omentum. Two dogs had enlarged regional mesenteric lymph nodes. One dog that presented with dysphagia had an oropharyngeal mass involving the larynx and cranial esophagus. Microscopically, there was transmural chronic sclerosing and granulomatous to pyogranulomatous inflammation with arteritis. Pythium spp. were identified in all specimens by immunohistochemistry.     

Mycobacterium avium infection in a dog

A 5-year old, spayed, mongrel was presented with intractable diarrhoea. Histopathologic examination of biopsy specimens taken during exploratory laparotomy revealed acid-fast organisms in the spleen, caecum, and colon. The dog was subsequently destroyed. At post-mortem, lesions were also observed in the liver and lymph nodes. Mycobacterium avium was cultured from splenic tissue. Infection of dogs with this organism is rare and the clinical picture described unusual.     

CT AND MRI FEATURES OF CAROTID BODY PARAGANGLIOMAS IN 16 DOGS

Carotid body tumors (paragangliomas) arise from chemoreceptors located at the carotid bifurcation. In imaging studies, this neoplasm may be confused with other neck neoplasms such as thyroid carcinoma. The purpose of this retrospective, cross‐sectional study was to describe computed tomographic (CT) and magnetic resonance imaging (MRI) characteristics of confirmed carotid body tumors in a multi‐institutional sample of dogs. A total of 16 dogs met inclusion criteria (14 examined using CT and two with MRI). The most common reason for imaging was a palpable cervical mass or respiratory signs (i.e., dyspnea or increased respiratory noises). The most commonly affected breed was Boston terrier (n = 5). Dogs were predominantly male castrated (n = 10) and the median age was 9 years [range 3–14.5]. Most tumors appeared as a large mass centered at the carotid bifurcation, with poor margination in six dogs and discrete margins in ten dogs. Masses were iso‐ to hypoattenuating to adjacent muscles in CT images and hyperintense to muscles in T1‐ and T2‐weighted MRI. For both CT and MRI, masses typically showed strong and heterogeneous contrast enhancement. There was invasion into the adjacent structures in 9/16 dogs. In six of these nine dogs, the basilar portion of the skull was affected. The external carotid artery was entrapped in seven dogs. There was invasion into the internal jugular vein in three dogs, and into the external jugular, maxillary, and linguo‐facial veins in one dog. Imaging characteristics helped explain some clinical presentations such as breathing difficulties, Horner's syndrome, head tilt, or facial nerve paralysis.     

Patterns of lymph node metastasis identified following bilateral mandibular and medial retropharyngeal lymphadenectomy in 31 dogs with malignancies of the head

Variable pathways of lymphatic drainage have been described in the dog head and neck. The aim of this study was to retrospectively assess the patterns of lymph node metastasis in dogs with malignancies of the head following bilateral mandibular and medial retropharyngeal lymphadenectomy. Thirty‐one dogs were included. Median age at surgery was 10 years (range: 5 months to 14 years) and mean bodyweight was 21.4 ± 11.9 kg. Lymph node metastasis occurred in 14 dogs (45%), with spread to mandibular lymph nodes in 14 dogs and medial retropharyngeal metastasis in 11 dogs. Eight of 13 dogs (62%) with lymphatic metastasis and a lateralised lesion showed contralateral dissemination, while 12/13 (92%) showed ipsilateral metastasis. Of 13 dogs with oral malignant melanoma, four showed metastasis to all four lymph centres. Contralateral metastasis may occur in dogs with malignancies of the head and should be considered during staging and management.