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

Abstract

This study describes epidemiologic, clinical, macro-and microscopic tumour characteristics and outcome in 97 cats with subcutaneous lymphoma, an uncommon variant of feline extranodal lymphoma. Middle-aged (median 11 years), male (60.8%), Domestic Shorthair cats (89.7%) were commonly affected. Most tumours presented as a painless, firm, subcutaneous nodule or mass, with predilection to the lateral thoracic or abdominal wall, and the interscapular region. Deep subcutaneous invasion with extension into superficial or underlying tissues, extensive central areas of necrosis and peripheral inflammation were characteristic histopathological findings. Prevalence of retroviral infection was low. Local relapses after therapy were common (43.5%), and 32.2% had distant involvement later in course. Median overall survival was 148 days. Subcutaneous lymphoma should be considered a rare but important differential diagnosis for a subcutaneous mass in cats. Tumours show an aggressive biological behaviour. Treatment options including prognosis should be investigated in further studies.

Cutaneous Lymphoma at Injection Sites

“…24 As an additional support to our findings, Meichner and von Bomhard 52 have voiced the suspicion of injection site reactions inducing lymphoma for a subgroup of recently described feline subcutaneous lymphomas. 52…”

“…In summary, cutaneous lymphomas arising in areas commonly used for injection resembled previously reported cases in cats 52 and that of human DLBLC-ACI 60,61 in which persistent chronic inflammation and immune stimulation in association with a favorable cytokine milieu lead to neoplastic transformation of lesional lymphocytes, facilitated in some instances by viral transformation. In conclusion, CLIS are angiocentric, angioinvasive, primary cutaneous that are predominantly large cell lymphomas with aggressive clinical behavior.…”

“…The latter is considered rare in dermal lymphomas 27,69,71 but has been recently reported as a common feature of feline subcutaneous lymphomas. 52 Likewise, the majority of CLIS of this study were DLBCLs. This is in contrast to previous reports for feline primary cutaneous lymphomas, which are predominantly of T-cell origin with a small cell morphology.…”

“…14,21,24,27,71 However, our data parallel recent findings of a predominance of a diffuse large cell morphology and a prevalent B-cell phenotype for feline subcutaneous lymphomas. 52 According to the MI, only 2 DLBCLs were medium grade, while 15 were low grade. This was an unexpected finding, especially since DLBCL, peripheral T-cell lymphoma (PTCL), and anaplastic large cell lymphoma (ALCL) tend to be intermediate to high grade.…”

“…44 In a subgroup of recently reported primary feline subcutaneous lymphomas, site of development (lateral thorax and interscapular region), clinical presentation as a single nodule, presence of necrosis leading to central cavitation, and peripheral inflammation were considered clinically highly suggestive of feline injection site sarcomas. 52 The aim of this report is to describe pathological features of a series of primary feline cutaneous lymphomas, which developed in sites of previous injections and were not preceded by sarcomas.…”