Nasal Tumors Research Articles

Treatment of advanced-stage canine nasal carcinomas with toceranib phosphate: 23 cases (2015-2020).

To determine the median survival time (MST) of dogs with nasal carcinoma treated with toceranib phosphate. The databases of four Spanish referral hospitals were retrospectively searched for dogs with a diagnosis of nasal tumours presented between January 2015 and October 2020. Dogs treated with radiotherapy or other chemotherapies prior toceranib were excluded. Twenty-three dogs with a confirmed nasal carcinoma treated with toceranib phosphate and with a CT scan for initial staging according to Adams Modified Staging System were included. Nine dogs had a stage III nasal carcinoma whereas 14 dogs had a stage IV nasal carcinoma. No dog had stages I and II nasal carcinoma. The median overall survival time was 139 days. The difference between the MST between dogs with stages III and IV was not statistically significant [P = 0.6, 140 days for stage III (range 46-401) vs 120 days for stage IV (range 23-600)]. Overall, dogs with epistaxis achieved a longer median survival (166 days) than dogs without epistaxis (83 days). Toceranib phosphate was generally well tolerated. Most dogs had an initial clinical benefit followed by progressive disease. This is the first study to report the MST in dogs with stages III and IV nasal carcinoma treated with toceranib phosphate. This retrospective study showed that toceranib phosphate decreases the clinical signs associated with nasal carcinomas.

Inverted Ductal Papilloma of the Salivary Gland

This is a case consult of slides stated to be from an excision of a buccal mucosa mass in a 58-year-old-man. The specimen was described as a 3 cm diameter roughly oval tan-gray tissue with a 2 x 1.5 cm mucosal ellipse on the surface that has a central ulcerated punctum. Cut section showed an underlying 1.7 cm diameter roughly oval well-circumscribed mass with a granular tan surface. Histological sections show a papillary lesion with an orifice on the mucosal surface and with epithelial nests invaginating into the underlying lamina propria in a non-infiltrative pattern. (Figure 1) The lesion is composed of papillary epithelial fronds with cleft-like spaces between the fronds. (Figure 2) The papillary fronds are lined by non-keratinizing basaloid stratified squamous cells with a superficial layer of columnar glandular cells along with mucous goblet cells interspersed among the squamous cells. (Figure 3) All the cellular components are devoid of cytologic atypia and mitoses. Based on these microscopic features we signed the case out as inverted ductal papilloma (IDP).
 
 Ductal papillomas are uncommon benign epithelial tumors with a papillary configuration that originate from the excretory ductal system of salivary gland acini.1-3 The World Health Organization recognizes two sub-types depending on the growth pattern: an intraductal papilloma (IP) and an IDP.1 An IDP usually presents as an asymptomatic submucosal nodule, measuring about 1.5 centimeters in diameter, and most commonly involving the buccal mucosa, followed by the lips, palate, and floor of the mouth.2,3 Histological sections typically show an unencapsulated though well-circumscribed epithelial proliferation with a papillary configuration on the luminal surface, and a nodular, endophytic or invaginating (“inverted”) configuration at its interface with the underlying lamina propria.2 Both the papillary and the invaginating areas are composed of basaloid, non-keratinizing stratified squamous epithelium that are often covered with a cuboidal or columnar ductal cell layer.2 Scattered among these are mucous goblet cells which can form microcysts.1,2 There is an overall morphological similarity to the sinonasal inverted papilloma.3 A relationship to trauma has been proposed.1,4 Association with Human Papilloma Virus (HPV) has also been reported.1 Others, however, have not been able to demonstrate this association.4
 
 Differential diagnoses primarily include IP - which is differentiated from IDP architecturally by being a unicystic intraluminal papillary proliferation within a dilated excretory duct 2 – and sialadenoma papilliferum – which is predominantly polypoid and pedunculated with a verrucoid surface rather than a submucosal nodule, and an over-all morphologic similarity to the cutaneous tumor syringocystadenoma papilliferum.1,4 An important differential diagnosis that has to be ruled out is mucoepidermoid carcinoma (MECA) because of the presence of both squamous and mucin-secreting cells. MECA is distinguished by poor circumscription, and an infiltrative solid-cystic growth pattern.2,4
 
 IDP is benign and non-recurrent. Unlike the nasal tumor, there has been no report of malignant transformation.2,3 Complete surgical excision is considered curative.1,2 Reporting these cases is encouraged to further our knowledge of the entity and elucidate a potential association with HPV.

Midfacial Degloving Technique for Free Flap Reconstruction of Nasal and Anterior Skull Base Defects.

Traditionally, surgical access for extirpation and reconstruction of midfacial tumors requires external incisions that can cause a myriad of complications, especially in irradiated patients. The modern midfacial degloving approach involves hidden, sublabial and intranasal incisions that provide reliable access for free flap reconstruction of nasal and maxillofacial tumors. Seven patients with a history of radiation therapy underwent free flap reconstruction of the midface. Five patients underwent the technique in a delayed manner, and the remaining two underwent reconstruction immediately at the time of resection. Five patients underwent free radial forearm fasciocutaneous free flaps and two underwent reconstruction with anterolateral thigh perforator flaps. Bone and/or rib cartilage grafting was used in all patients. All patients underwent successful free flap reconstruction of the midface without external incisions. The most common complication was postoperative infection requiring oral or intravenous antibiotics. No patients sustained loss of their grafts or hardware in the postoperative period. The midfacial degloving technique provides satisfactory exposure to the nasal cavity, midface, orbits, and skull base for free flap reconstruction, without disrupting the external soft tissue. The authors describe a novel use of the midfacial degloving technique to provide safe and reliable results with improved cosmetic outcome.

Adult T cell- leukemia/lymphoma associated with HTLV-1 presenting as giant mass of the face

A 30-year-old Arabic woman of low socio-economic status, without medical history of HIV infection, presented to our department for neglected giant mass of the face evolving for 2 years. She was treated for long time with herbal traditional treatments, which explains the delay of consultation. Physical examination revealed a bulky tumor, of reddish-brown color, occupying the entire face below the franc, more lateralised on the left side. The right eye had restricted movement, while the left eye was fixed (Panel A,B). CT scan showed a nasal cavity tumour with orbital and maxillary sinus invasion, without intra cranial extension or distant metastasis. Laboratory testing was positive for HTLV I/II and she was negative for HIV. Surgical biopsy with histo-pathological study established the diagnosis of HTLV-1 associated adult lymphoma/leukaemia, with strong CD4 and CD25 antibody staining. She received chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) regimen, but she died after two cycles.

Nasal Septum Glomus Tumor: A Rare Cause of Unilateral Nasal Obstruction.

Nasal Septum Glomus Tumor: A Rare Cause of Unilateral Nasal Obstruction.

Reconstruction after big nasal tumors

This article comes as a presentation of the clinical experience in the plastic surgery department. Gather the experience of 3 clinical cases, more representative, with different histopathological tumors, of important dimensions that occupied a large part of the facial anatomical unit, the nose. The article is structured by presenting the risk factors that are the causes of malignant lesions and by recalling the therapeutic options and general principles of addressing large lesions. Malignant lesions that occur most frequently in the nose are reviewed. We consider that it is a serious health problem, with various consequences, of a functional nature, which can affect the airways and aesthetically that can lead to a reconsideration of self-respect and the perception of the affected person towards his peers. The approach of the cases was done sequentially. The first surgical stage involved the excision of the lesion with the oncological safety limit, the defect being larger than the lesion and the more elaborate therapeutic options on the reconstruction scale. The first operative stage ended each time with covering the defect with a graft to have the confirmation of the histopathological examination, free of the tumor. The second stage of the treatment involved lifting the flap and accommodating it. The last surgical stage involved the sectioning of the pedicle and its reintegration into the donor area.

Surgical Treatment and Reconstruction of Nasal Defects According to the Aesthetic Subunits Principles.

The aim of this study was to determine the prevalence of nasal skin cancer, its location by facial aesthetic subunits and the type of reconstructive procedures performed for each nasal subunit after excision for nasal skin tumors. Observational cross-sectional study of all consecutive patients with the diagnosis of skin tumor located in the nasal unit, treated from 2018 to 2019 by the department of head and neck surgery of a general hospital. 60 patients were treated with nasal skin tumors excisions. A total of 52 patients (86,6%) had basal cell skin cancer, 7 (11,6%) had squamous cell skin cancer and 1 (1,6%) had melanoma. Fifty-nine patients (98.33%) presented a primary tumor and just 1 case (1,66%) recived a previous surgical treatment. Regardless of the type of tumor, the tip subunit was the most often involved with 29 (48,33%) cases in total. Despite of the nasal aesthetic subunit affected, the most frequent type of procedure used for reconstruction was the rotation or advancement flap, based on aesthetic nasal subunits, which was performed in 39 cases (65%). Nasal reconstruction after skin cancer can be very complex, especially since all patients have high expectations about the results. In order to achieve good results, there is a necessity for careful analysis of the defect, correct planning and excellent technical execution of the procedures Frequently, staged procedures will be needed to achieve an optimal result.

Review of the cytological features of olfactory neuroblastoma: A retrospective single-center study.

Olfactory neuroblastoma (ONB) is a rare malignant neuroectodermal tumor. Due to the rarity, there are scarce reports describing the cytological features of ONB. Thus, we aimed to analyze these cytological features and discuss their differences depending on the histological grading of ONB. Patients with a histopathological diagnosis of ONB who underwent fine-needle aspiration cytology were enrolled in the study. The cytological features, including arrangement and shape of neoplastic cells, nuclear features, and presence of rosettes, were analyzed. Eight patients with ONB were enrolled; cytological specimens of seven patients were obtained from metastatic lesions and that of one patient were obtained from the nasal cavity tumor. The cytological specimens demonstrated variable-sized clusters of neoplastic cells and single cells. Two-cell pattern, composed of large-sized viable neoplastic cells and small-sized apoptotic cells, was noted in 3 of 4 high-grade ONBs but in none of 4 low-grade ONBs. This reflects that the presence of the two-cell pattern may represent higher proliferation in neoplastic cells. The neoplastic cells had scant cytoplasm and round to oval nuclei containing fine to granular chromatin without conspicuous nucleoli. Rosettes and paranuclear blue bodies were observed in one patient. Most cytological specimens of ONB were obtained from metastatic lesions, especially from the cervical lymph node. Thus, ONB should be differentiated from malignant lymphoma and small cell neuroendocrine carcinoma. Recognition of these cytological features of ONB while considering patient history can aid in correctly diagnosing ONBs. Moreover, the presence of two-cell pattern might reflect high-grade histology of ONB.

Utility of CT texture analysis to differentiate olfactory neuroblastoma from sinonasal squamous cell carcinoma

The purpose of this study was to examine differences in texture features between olfactory neuroblastoma (ONB) and sinonasal squamous cell carcinoma (SCC) on contrast-enhanced CT (CECT) images, and to evaluate the predictive accuracy of texture analysis compared to radiologists’ interpretations. Forty-three patients with pathologically-diagnosed primary nasal and paranasal tumor (17 ONB and 26 SCC) were included. We extracted 42 texture features from tumor regions on CECT images obtained before treatment. In univariate analysis, each texture features were compared, with adjustment for multiple comparisons. In multivariate analysis, the elastic net was used to select useful texture features and to construct a texture-based prediction model with leave-one-out cross-validation. The prediction accuracy was compared with two radiologists’ visual interpretations. In univariate analysis, significant differences were observed for 28 of 42 texture features between ONB and SCC, with areas under the receiver operating characteristic curve between 0.68 and 0.91 (median: 0.80). In multivariate analysis, the elastic net model selected 18 texture features that contributed to differentiation. It tended to show slightly higher predictive accuracy than radiologists’ interpretations (86% and 74%, respectively; P = 0.096). In conclusion, several texture features contributed to differentiation of ONB from SCC, and the texture-based prediction model was considered useful.

Comparison of CT features of 79 cats with intranasal mass lesions.

ObjectivesThis retrospective multicentre study compared the CT characteristics of cats diagnosed with intranasal mass lesions to determine if defining imaging features exist between different tumour types and between neoplastic and non-neoplastic lesions.MethodsThe medical records of two institutions were reviewed for cats with CT findings consistent with an intranasal mass lesion with subsequent histopathological examination. For each CT scan the mass location, growth pattern, margin distinction, contrast enhancement pattern and presence of intralesional areas of mineralisation or necrosis were recorded. The presence of facial deformity, the location and type of bone changes, extranasal extension of the mass lesion and the regional lymph nodes size, contrast pattern and hilus visibility were also documented.ResultsThirty-five cats with nasal lymphoma, 28 cats with non-lymphomatous nasal neoplasia (carcinoma or sarcoma) and 16 cats with inflammatory lesions met the inclusion criteria. Cats with non-lymphomatous nasal neoplasia were more likely to show unilateral nasal changes (odds ratio [OR] 3.9), areas of intralesional calcification (OR infinity) and extension of the mass lesion within the frontal sinus (OR 4.5), while cats suffering from nasal lymphoma were more likely to show a mixed (OR 4.5) and expansile growth pattern (OR 7.8), and a regional lymphadenomegaly (OR 2.4). The CT findings in cats diagnosed with inflammatory mass-like lesions were highly variable and overlapped with findings for nasal neoplasms but were significantly associated with the absence of bony changes to the nasal cavity boundaries (OR 10.2).Conclusions and relevanceFindings from the current study support the ability of CT to aid in the discrimination of tumour type in cats presented with an intranasal mass lesion.

Neoplasia-Associated Wasting Diseases with Economic Relevance in the Sheep Industry

Simple SummaryNeoplasia is a common cause of weight loss and emaciation. Despite its relative infrequency in sheep, there are three neoplastic diseases with special relevance. Small intestinal adenocarcinoma (SIA), ovine pulmonary adenocarcinoma (OPA) and enzootic nasal adenocarcinoma (ENA) are three neoplastic diseases with economic impact in the sheep industry. They mostly occur at ages under common production cycles, have epidemiological relevance in sheep rearing countries, and two of them (OPA and ENA) have an infectious aetiology. SIA occurs elsewhere in the world but has a special economic impact in Australia and New Zealand. OPA and ENA have relevant economic significance in most continents but have not been recorded in Australia and New Zealand. In this review, we focus on the epidemiology, clinicopathological features, pathogenesis and the diagnostic tools currently available for the diagnosis of these three neoplastic diseases.We review three neoplastic wasting diseases affecting sheep generally recorded under common production cycles and with epidemiological and economic relevance in sheep-rearing countries: small intestinal adenocarcinoma (SIA), ovine pulmonary adenocarcinoma (OPA) and enzootic nasal adenocarcinoma (ENA). SIA is prevalent in Australia and New Zealand but present elsewhere in the world. This neoplasia is a tubular or signet-ring adenocarcinoma mainly located in the middle or distal term of the small intestine. Predisposing factors and aetiology are not known, but genetic factors or environmental carcinogens may be involved. OPA is a contagious lung cancer caused by jaagsiekte sheep retrovirus (JSRV) and has been reported in most sheep-rearing countries, resulting in significant economic losses. The disease is clinically characterized by a chronic respiratory process as a consequence of the development of lung adenocarcinoma. Diagnosis is based on the detection of JSRV in the tumour lesion by immunohistochemistry and PCR. In vivo diagnosis may be difficult, mainly in preclinical cases. ENA is a neoplasia of glands of the nasal mucosa and is associated with enzootic nasal tumour virus 1 (ENTV-1), which is similar to JSRV. ENA enzootically occurs in many countries of the world with the exception of Australia and New Zealand. The pathology associated with this neoplasia corresponds with a space occupying lesion histologically characterized as a low-grade adenocarcinoma. The combination of PCR and immunohistochemistry for diagnosis is advised.

Intranasal diffuse large B-cell lymphoma of immunoblastic type with extensive osteolysis in a dog

This report describes a rare case of nasal lymphoma in a dog. A stray dog was presented with a swollen snout showing ulcerations and sanguinopurulent discharges. Cytological evaluation of fine-needle aspiration specimens revealed discrete round cell tumor presumed as B-cell lymphoma. Histopathological examination and immunohistochemistry staining of biopsy confirmed diffuse large B-cell lymphoma of immunoblastic type. This case is one of the rare reports of nasal lymphoma in dogs and the first immunoblastic type. Our finding emphasizes the significance of considering lymphoma in differential diagnosis of nasal tumors in dogs.

LC-MS/MS Analysis of the Formation and Loss of DNA Adducts in Rats Exposed to Vinyl Acetate Monomer through Inhalation.

Formation of DNA adducts is a key event during carcinogenesis. DNA adducts, if not repaired properly, can lead to mutations and cancer. DNA adducts have been frequently used as biomarkers to evaluate chemical exposure. Vinyl acetate monomer (VAM) is widely used in the manufacture of various industrial polymers. Previous studies have documented that VAM induced nasal tumors in rodents exposed to high exposure levels of VAM. VAM is metabolized by carboxylesterase to acetaldehyde (AA), which subsequently results in DNA adducts. However, AA is also an endogenous metabolite in living cells, which impedes accurate assessment of the contribution of VAM exposure under the substantial endogenous background. To address this challenge, we exposed rats to stable isotope labeled [13C2]-VAM at 50, 200, and 400 ppm through inhalation for 6 h, followed by DNA adduct analysis in nasal respiratory and olfactory epithelia with highly sensitive mass spectrometry. Our results show that exogenous N2-ethyl-dG adducts were present in all rats exposed to [13C2]-VAM, with over 2-fold higher DNA adducts in nasal respiratory epithelium than olfactory epithelium. Our data also show that N2-ethyl-dG is a more sensitive biomarker to assess VAM exposure than 1,N2-propano-dG adducts. Moreover, a very low amount of exogenous N2-ethyl-dG adducts were detected in peripheral blood mononuclear cell samples of exposed rats, suggesting that only an extremely small percentage of [13C2]-VAM or its metabolite may enter into systemic circulation to potentially damage tissues beyond nasal epithelium. Furthermore, exogenous N2-ethyl-dG DNA adducts undergo rapid repair or spontaneous loss in nasal epithelium of exposed rats. Taken together, the results presented herein provide novel quantitative data and lay the foundation for future studies to improve risk assessment of VAM.

Long-term risk of subsequent cancer incidence among hereditary and nonhereditary retinoblastoma survivors

BackgroundIncreased sarcoma and melanoma risks after hereditary retinoblastoma are well established, whereas less is known about epithelial subsequent malignant neoplasms (SMNs) and risks for multiple (≥2) SMNs.MethodsLeveraging long-term follow-up and detailed histologic information, we quantified incident SMN risk among 1128 hereditary and 924 nonhereditary retinoblastoma survivors (diagnosed 1914–2006; follow-up through 2016). Standardised incidence ratios (SIRs) compared cancer risk after retinoblastoma relative to the general population. We estimated cumulative incidence accounting for competing risk of death.ResultsHereditary survivors had statistically significantly increased SMN risk (N = 239; SIR = 11.9; 95% confidence interval [CI] 10.4–13.5), with SIRs >80-fold for sarcomas, nasal cavity tumours and pineoblastoma. Significantly increased risks were also observed for melanoma and central nervous system, oral cavity and breast SMNs (SIRs = 3.1–17), but not the uterus, kidney, lung, bladder, pancreas or other types. Cumulative incidence 50 years following hereditary retinoblastoma was 33.1% (95% CI 29.0–37.2) for a first SMN and 6.0% (95% CI 3.8–8.2) for a second SMN. SMN risk was not increased after nonhereditary retinoblastoma (N = 25; SIR = 0.8; 95% CI 0.5–1.2).ConclusionBeyond the established sarcoma and melanoma risks after hereditary retinoblastoma, we demonstrate increased risk for a more limited number of epithelial malignancies than previously suggested. Cumulative incidence estimates emphasise long-term SMN burden after hereditary retinoblastoma.

The Nose that Broke the Hip! Tumor Induced Osteomalacia Secondary to Phosphaturic Mesenchymal Nasal Tumor : A Case Report.

Tumor induced osteomalacia is a rare paraneoplastic syndrome caused by usually small mesenchymal tumors. The tumors are commonly located in the extremities whereas occurrence in the nasal cavity is quite rare. An 18 year old male presented with asymmetric weakness of both lower limbs and difficulty in walking since one year. On evaluation he was found to have open femur head physes and iliac apophyses, low serum Phosphorus, low vitamin D, normal serum calcium, elevated PTH & alkaline phosphatase levels. FGF-23 levels in serum were elevated. DOTA NOC PET CT revealed tumor in the left nasal cavity abutting the nasal septum. Surgical excision of the tumor resulted in normalisation of the serum levels of phosphorus, vitamin D and FGF-23. This case report indicates the importance of maintaining high clinical suspicion and early detection of causative tumor using appropriate imaging techniques.

Non-resolving acute sinusitis due to nasal hamartoma: a case report

The paranasal sinuses are closely related to vital structures, and therefore, rhinosinusitis may lead to various dangerous complications. Nasal chondromesenchymal hamartoma is a rare benign lesion of the sinonasal tract in children and adolescents. We report the case of a 15-year-old patient with antibiotic-refractory acute sinusitis in whom a nasal tumor was identified and histopathologically diagnosed as a hamartoma. Therefore, the tumor was removed surgically to alleviate the patient’s symptoms. This case highlights the necessity of investigating the underlying cause if conventional treatment fails to resolve a mild disease like acute sinusitis. To the best of our knowledge, this is the first reported case of a chondro-osseous respiratory epithelial adenomatoid hamartoma presenting with acute sinusitis.

Adult embryonal rhabdomyosarcoma of the nose and paranasal sinuses misdiagnosed as an orbital cellulitis: a case report

 Rhabdomyosarcoma is a primary malignant tumor, which develops from normal skeletal muscle tissue. It´s a tumor quite common in children and exceptional in adults. This tumor constitutes a diagnostic and therapeutic emergency based on multidisciplinary management. We present the case of a 22-year-old woman admitted for left orbital swelling and purulent rhinorrhea initially considered as orbital cellulitis. The unsatisfactory outcome under oral and topical antibiotic therapy justified a biopsy of the lesion revealing embryonal rhabdomyosarcoma. A treatment combining chemotherapy and radiotherapy was immediately indicated and started. This protocol is increasingly accepted because of its low morbidity. Although facial rhabdomyosarcoma is relatively rare, it should be considered as a potential differential diagnosis of nasal and paranasal sinus tumors not only in children, but also in adults. The originality of our case is due to the young age of our patient and the histological type of the tumor.

Clinicopathological findings in ethmoidal nasal tumour in madras red sheep

Clinicopathological findings in ethmoidal nasal tumour in madras red sheep

Efficacy of chemotherapy and palliative hypofractionated radiotherapy for cats with nasal lymphoma.

Nasal lymphoma (NL) is the most common nasal tumor in cats, and radiotherapy, chemotherapy, or a combination of these treatments have been described as the treatment for this disease. However, the previous studies included various machines and protocols of radiotherapy. Therefore, we aimed to retrospectively compare the prognosis among cases treated with palliative hypofractionated radiotherapy, chemotherapy, and a combination of them with united machine and protocol of radiotherapy. When compared overall survival and progression free survival, there was no significant difference among these three groups. The data of this study suggested that similar efficacy could be achieved by palliative hypofractionated radiotherapy, chemotherapy, or a combination of them.

Exogenous Small Ruminant Betaretrovirus Envelope Protein Is Detected in Draining Lymph Nodes in Contagious Respiratory Tumors of Sheep and Goats.

Contagious respiratory tumors of sheep and goats are epithelial neoplasms of the lung and nasal cavities. They are associated with oncogenic betaretroviruses known as jaagsiekte sheep retrovirus and enzootic nasal tumor retrovirus of sheep and goats. We investigated the presence of the envelope protein (ENV) of these retroviruses in retropharyngeal and mediastinal lymph nodes using a specific monoclonal antibody by immunohistochemistry methods, single-labeled or combined with ovine B or T lymphocytes or macrophage cell markers. Samples of lymph nodes, fixed in formalin and zinc fixative, were obtained from paraffin-embedded material. Four groups of samples were used: 24 natural cases of ovine pulmonary adenocarcinoma (OPA), 13 of enzootic nasal adenocarcinoma of sheep (ENAS), 19 of enzootic nasal adenocarcinoma of goats (ENAG), and 14 control samples. ENV was detected by single labeling in cortical lymphoid follicles. Six of 24 OPA samples were positive and only in those from sheep with extensive neoplasia. Immunolabeling was detected in 5/13 ENAS and 10/19 ENAG samples. Positive labeling was found either in the intercellular spaces, membranes, or cytoplasm of cells in follicles. Control samples were not correspondingly labeled. Double immunohistochemistry demonstrated co-labeling of ENV and CD21 (B cells and follicular dendritic cells) in all samples, CD14 (macrophage) in OPA samples, and Pax-5 (B cells) in ENAG samples, but not with CD8 or CD4 (T lymphocytes). These results demonstrate the presence of betaretrovirus ENV proteins in nontumor cells in regional lymph nodes in sheep and goats with contagious respiratory tumors.