Pulmonary lymphomatoid granulomatosis in a dog: evidence of immunophenotypic diversity and relationship to human pulmonary lymphomatoid granulomatosis and pulmonary Hodgkin's disease

Angioinvasive lymphoma (lymphomatoid granulomatosis) in a cat, with cutaneous and ocular metastasis

Lymphomatoid granulomatosis (LYG) is a rare variant of an angioinvasive T-cell lymphoproliferative disorder that primarily affects the lungs, with common sites of metastasis including the skin and subcutis. In humans, it is a B-cell lymphoproliferative disorder associated with Epstein-Barr virus infection. Our case is a 7-y-old, spayed female, domestic longhair cat that decompensated and was euthanized following an initial diagnosis of angioinvasive lymphoma from a skin biopsy. Autopsy revealed nodules in the lungs and subcutis, and corneal thickening and cloudiness. Histologic examination of cutaneous nodules, lungs, and eye showed similar angioinvasive cellular infiltrates and pattern to that of the original skin biopsy, consistent with a diagnosis of LYG. The neoplastic cells displayed CD3-positive immunoreactivity in the skin, eye, and lung, and PCR for antigen receptor rearrangement (PARR) showed T-cell clonality in all tissues tested. This is the third case of LYG to be reported in cats and is the only case in which PARR analysis and immunophenotyping immunohistochemical staining was performed. LYG with ocular involvement has not been reported previously in cats, to our knowledge. Our case demonstrates the necessity for considering LYG when presented with a cat with respiratory signs in conjunction with subcutaneous nodules and ocular lesions.

CD30 Cross-Reactivity and Expression in Feline Normal Tissues and Lymphomas

CD30 is a transmembrane glycoprotein of the tumor necrosis factor receptor superfamily included in the diagnostic algorithm of human cutaneous, anaplastic large cell and Hodgkin lymphomas and represents an optimal therapeutic target for CD30⁺ tumors. Similar diagnostic and therapeutic approaches are largely missing for feline lymphomas. Cross-reactivity of the antihuman CD30 receptor clone Ber-H2 was investigated in feline lymphomas. Comparative analysis of feline and human CD30 identified 61% identity of the amino acid sequence, with 100% identity of the main sequence of the epitope targeted by the antibody (RKQCEPDYYL). CD30 expression in normal feline tissues was restricted to rare lymphoid cells in perifollicular and interfollicular lymph node areas and in the thymic medulla. In feline lymphoma, CD30 was expressed in 4 of 33 (13%) T-cell lymphomas, 3 of 22 (14%) B-cell lymphomas, and 5 of 7 (71%) mixed-cell lymphomas, showing diffuse (1/5) or multifocal (4/5) positivity restricted to neoplastic multinucleated lymphoid cells and binucleated cells consistent with Reed-Sternberg-like cells. Based on the human classification system, cell morphology, expression of multiple markers (mixed cell components), and CD30 positivity, these cases were considered most consistent with classical Hodgkin-like lymphoma (HLL). The other 2 mixed-cell lymphomas were CD30 negative and thus most consistent with either T-cell-rich large B-cell lymphoma (TCRLBCL) or nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL). These findings provide multiple data supporting the cross-reactivity of the Ber-H2 anti-CD30 clone in feline tissues and give evidence of the usefulness of CD30 in the diagnostic evaluation of feline lymphoma.

Anaplastic Large T-Cell Lymphoma in the Intestine of Dogs

Anaplastic large T-cell lymphoma (ALTCL) is a rare subtype of non-Hodgkin T-cell lymphoma that occasionally occurs in the gastrointestinal tract of humans. Enteropathy-associated T-cell lymphoma (EATL) type 1 is the most common type of intestinal lymphoma in dogs, and ALTCL has not previously been reported in the intestinal tract of dogs. Thirteen dogs with intestinal masses diagnosed as intestinal lymphoma with anaplastic morphology were reviewed. Clinical data, including treatment protocols, were available for 11 cases. Immunohistochemistry for CD3, CD20, and CD30 was performed for all cases in addition to PCR for Antigen Receptor Rearrangements (PARR) for assessment of clonality. Eight (62%) of the cases presented with intestinal perforation, and all cases had 1 or more masses arising from the small intestine. Histologically, all cases were characterized by transmural infiltrates of large, CD3-positive and frequently CD30-positive cells. Neoplastic T cells had marked anisocytosis and anisokaryosis, prominent nucleoli, and occasionally indented to reniform nuclei. There was abundant necrosis and inflammation with occasional vascular invasion within neoplastic masses. All cases had a monoclonal T-cell receptor γ gene rearrangement. The median survival time was 5 days, with 1 dog surviving 2 years after the initial diagnosis. ALTCL can occur as an aggressive transmural lymphoma in the gastrointestinal tract of dogs and commonly causes intestinal perforation. ALTCL can be differentiated from EATL type 1 and might have implications for accurate prognostication and selection of therapeutic options in the future.

Subcutaneous Panniculitis-Like T-cell Lymphoma in Dogs: Morphologic and Immunohistochemical Classification

Canine nonepitheliotropic cutaneous T-cell lymphomas (NECTCL) are poorly characterized. In humans, a number of distinct subtypes of NECTCL have been recognized, including subcutaneous panniculitis-like T-cell lymphoma (SPTCL). Five dogs with subcutaneous T-cell lymphomas histologically similar to SPTCL in humans are herein described. The mean age was 8.5 years (5.5 to 12 years). No breed or sex predilection was identified in this small cohort. Two dogs presented with an acute onset of multiple skin masses and 3 dogs had solitary masses with subsequent development of multiple smaller masses within 0.5 to 2 months post-diagnosis without treatment. Locations, when specified, included shoulder, neck, and ventral abdomen. Two dogs were euthanized following diagnosis and one dog treated with chemotherapy (CCNU) survived 7 months post-diagnosis. Histologically, all cases were characterized by proliferations of either small to intermediate or large sized, CD3-positive T cells that infiltrated the subcutis in a lace-like pattern and frequently rimmed adipocytes. No epitheliotropism was observed, neoplastic cells were often karyorrhectic, and there were regions of extensive necrosis. Heavy infiltrates of histiocytes with prominent phagocytosis masked the lymphoid neoplastic cell population in some sections. A clonal T-cell receptor gamma gene rearrangement was found in 4 of the 5 cases. While SPTCLs typically have a less aggressive clinical course in humans, their biological behavior in dogs remains to be determined. In summary, SPTCL may represent a distinct entity in dogs and needs to be accurately diagnosed to better determine clinical behavior.

Diagnosis of anaplastic large-cell lymphoma in a dog using CD30 immunohistochemistry

Anaplastic large-cell lymphoma or null-cell lymphoma is a clinical entity reported in people, classified according to the unique appearance of large pleomorphic cells that express CD30. Null-cell lymphoma has also been described in dogs when neither CD3 nor CD79α is expressed by the tumor. We describe a case of lymphoma in the dog in which neoplastic cells did not express routine B- or T-lymphocyte markers on flow cytometry or immunohistochemistry; however, cells immunohistochemically labeled for CD30. The dog in our case died 5 mo after initial presentation, confirming a poor prognosis. Identification of further similar cases in dogs would provide additional prognostic information for this subset of lymphomas. CD30 may also serve as a potential therapeutic target in anaplastic large-cell lymphomas.

Pulmonary angiocentric lymphoma (lymphomatoid granulomatosis) in a donkey

A 36-year-old donkey developed dyspnoea, pyrexia, hypoalbuminaemia and oedema. Following continued clinical deterioration the donkey was humanely destroyed. Grossly, there were numerous nodules (5-10mm) scattered throughout the lung. Microscopically, the lung was infiltrated by an angiocentric and bronchocentric to diffuse mixed population of small mature and atypical lymphocytes, histiocytes, plasma cells and fewer eosinophils. The infiltrate was composed of numerous small mature and fewer atypical CD3(+) T lymphocytes. Low numbers of CD20(+) and CD79a(+) B cells, some atypical, accompanied the T cells. These infiltrates were consistent with an angiocentric lymphoma and resembled lymphomatoid granulomatosis, an Epstein-Barr virus (EBV)-associated human tumour. Immunohistochemistry for EBV latent membrane protein and polymerase chain reaction analysis for equine gamma herpesvirus DNA were negative. To the authors' knowledge this is the first case of angiocentric lymphoma reported in a donkey and the first case of lymphomatoid granulomatosis-type disease in an animal in which possible concurrent infection with a gamma herpesvirus has been investigated.

Successful management with CHOP for pulmonary lymphomatoid granulomatosis in a dog

A 3-year-old, spayed female miniature dachshund was presented for vomiting and anorexia. Thoracic radiographs and CT scan revealed abnormal pulmonary opacities at bilateral caudal lobe. Cytological analysis of the pulmonary mass revealed the presence of large lymphohistiocytic cells and small lymphocytes with occasional neutrophils and plasma cells. An open lung biopsy was performed and a diagnosis of pulmonary lymphomatoid granulomatosis (LYG) was made. The dog was administered CHOP based therapy (modified UW-25), and it survived for 1,022 days after admission. Immunohistochemistry revealed pulmonary lesions consisted of many CD79a positive B cells aggregation and proliferation with prominent angiocentric pattern. This was the first case of canine pulmonary LYG managed by CHOP chemotherapy.

A case of canine lymphomatoid granulomatosis with cutaneous lesions

A 10-year-old, castrated, mixed-breed dog presented with a 1.5-month history of scattered, crateriform ulcers on the trunk and extremities. Some skin lesions appeared to regress spontaneously, but new lesions developed. Thoracic radiography revealed pulmonary consolidated lesions suggestive of tumor. A skin biopsy was performed for histopathological, immunohistochemical and clonality analyses. Histopathological examination of the cutaneous lesion revealed an intense infiltration of atypical lymphoid cells with some other cell populations around the blood vessels in the dermis. Atypical lymphoid cells were shown to be CD3-positive in the immunohistochemical analysis. The presence of clonally expanded T-cells was revealed by the clonal rearrangement of T-cell receptor gamma-chain gene. From the above findings, the dog was diagnosed with lymphomatoid granulomatosis.

Metastatic angioinvasive lymphoma (lymphomatoid granulomatosis) in a cat

A subcutaneous mass removed from the right rear leg of a 17-year-old, spayed, female Domestic Shorthair cat was characterized histopathologically by granulomatous inflammation, sheets of large atypical lymphoid cells, and necrosis. The walls of the small and medium caliber blood vessels were invaded transmurally by atypical lymphoid cells. A diagnosis of angioinvasive lymphoma (AIL), or lymphomatoid granulomatosis, was made based on histopathologic findings. The cat was euthanized 2 months later because of recurrence of the mass and elevated serum alanine aminotransferase activity, and a necropsy was performed. The histopathologic lesion of AIL was seen in the skin and subcutis of the right rear leg, and neoplastic cell infiltrates were seen in adjacent skeletal muscle, right superficial inguinal lymph node, liver, and spleen. By immunohistochemistry, variable numbers of neoplastic cells expressed B-lymphocyte antigen 36 (BLA36) or cluster of differentiation (CD)3 markers, indicative of B- and T-cell lineages, respectively. Neoplastic cells were uniformly positive for vimentin and uniformly negative for cytokeratins and myeloid/histiocytic antigen. Although the cat had received a Rabies virus vaccine subcutaneously in the right rear leg 6 months earlier, the AIL lesion was not typical of vaccine-induced sarcomas. The AIL in this cat was unusual because the extrapulmonary metastases involved the skin and subcutis.

A case of canine vasotropic and vasoinvasive nonepitheliotropic lymphoma with unusual tumor cells and extensive dermal necrosis

A 14-year-old, spayed female Shih-tzu dog presented with masses in the dorsal aspect of cervical region and digit of the right anterior limb. Extensive necrosis was seen in the dermal tissue overlying the tumor, and diffuse round cell proliferation and infiltration were seen histologically from the superficial dermis to the deep dermis. Two types of proliferating cells were present: lymphoblast-like cells with round-oval, vesicular nuclei and moderate-large nucleoli; and smaller cells with characteristic irregularly shaped nuclei. Electron microscopy of these smaller cells showed cerebriform, pleomorphic nuclei with a chromatin pattern characteristic of lymphoid cells, as seen in lymphoblast-like tumor cells. Immunohistochemically, both types of tumor cells were positive for CD3. Most vessel walls had been invaded by tumor cells, resulting in extensive dermal necrosis and hemorrhage. Based on these histopathological findings, the tumor was diagnosed as vasotropic and vasoinvasive nonepitheliotropic lymphoma, characterized by a notable presence of unusual tumor cells with irregularly shaped nuclei and extensive dermal necrosis.