Metastatic Angioinvasive Lymphoma (Lymphomatoid Granulomatosis) in a Cat

Abstract

Abstract. 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.

Patient characteristics, histopathological findings and outcome in 97 cats with extranodal subcutaneous lymphoma (2007–2011)

“…However, one case series reported different lymphoma types in cats with a history of FISS and suspected similar risk factors for the development of both neoplasms . Another report of a cat with a subcutaneous angioinvasive lymphoma also hypothesized a possible causality between the tumour and a rabies vaccine the cat received 6 months prior at the same location . Probably a reactive, longstanding, polyclonal lymphocytic inflammation might progress to a monoclonal, neoplastic population later in course, which was shown so far in humans .…”

“…There are a few reports about epidermal and dermal forms, and even less is known about subcutaneous involvement. To the authors' knowledge only few cases of lymphoma affecting the subcutaneous tissue have been described in the literature so far . Generally, those cases were included in studies together with different lymphoma subtypes …”

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

“…Lymphomatoid granulomatosis (LYG) is an extremely rare variant of lymphoma reported in humans and dogs, and has only been reported twice in cats, to our knowledge. 7,12,13…”

“…3,6 Immunophenotypic characterization was only defined in one of the previously reported feline cases in which, again, a mixed population was reported with BLA36 and CD3 positivity suggestive of B and T cell, respectively. 7,12 Dogs often develop eosinophilia, lymphocytosis, and hyperglobulinemia. 1,2,4 In cats, reported sites include lungs, liver, spleen, skin, and subcutis, with clinical signs and aberrations in biochemical parameters related to the affected organ.…”

“…The disease in cats carries a grave prognosis, with reported survival times of ~2 mo from time of diagnosis. 7,12…”