Canine Splenic Nodular Lymphoid Lesions: Immunophenotyping, Proliferative Activity, and Clonality Assessment

Abstract

Canine splenic lymphoid nodules are currently classified as indolent lymphomas (marginal zone lymphoma [MZL], mantle cell lymphoma [MCL]) or nodular hyperplasia (lymphoid [LNH] or complex [CNH] type). Their differentiation can be difficult on morphology, because of similar histologic appearance and poorly defined diagnostic criteria. Thirty-five surgical samples of splenic lymphoid nodules were reviewed in order to assess the diagnostic contribution of immunophenotyping, proliferative activity and clonality (PARR) in differentiating between hyperplastic and neoplastic lesions. Proliferative activity was evaluated by double immunolabeling for Ki-67 and CD79a, in order to separately assess the proliferative activity of B cells and non-B cells. Definitive diagnoses were MZL ( n = 11), MCL ( n = 4), LNH ( n = 10), and CNH ( n = 10). The overall concordance between histology and PARR was above 90%. Lymphomas had a significantly higher percentage of CD79a-positive areas (mean, 36.30%; P = .0004) and a higher B-cell proliferative activity (median Ki-67 index, 5.49%; P = .0012). The threshold value most accurately predicting a diagnosis of lymphoma was ≥28% of B-cell areas, with a Ki-67 index above 3%. Dogs were monitored for a median follow-up time of 870 days (IQR, 569-1225), and no relapses were documented. Overall median survival time was 1282 days. The combination of histology, immunohistochemistry and PARR can improve the diagnostic accuracy for canine splenic lymphoid nodules, although the long-term behavior of these lesions appears similar.

Cyclin D1 immunohistochemical expression and somatic mutations in canine oral melanoma

“…These data may be explained by the high proliferative rate of this tumour . This is also confirmed by the elevated expression of Ki‐67 protein, a widely used proliferation marker, in our COM cases as compared to other canine tumours such as mast cell tumours, indolent lymphoma, gastrointestinal stromal tumours, mammary tumours, peripheral nerve sheath tumours and gliomas …”

Evaluation of cytological diagnostic accuracy for canine splenic neoplasms: An investigation in 78 cases using STARD guidelines

“…This is a risk that pathologists have to bear in mind; thus the diagnosis of nodular low-grade lymphoma should be supported by histological evaluation of architectural changes, especially in dogs. A recent report [60] has demonstrated a high overall concordance between histopathology, immunohistochemistry and PCR for antigen receptor rearrangement (PARR) in the diagnosis of marginal zone lymphoma, mantle cell lymphoma and lymphoid or complex nodular hyperplasia. Therefore, further development of combined methods also applicable to cytological specimens may provide a less invasive and more valuable diagnostic approach to the diagnosis of splenic nodular lymphoid lesions.…”

Use of contrast-enhanced ultrasound for assessment of nodular lymphoid hyperplasia (NLH) in canine spleen

“…Furthermore, in a routine work, as cytology is often involved, it is quite impossible to discern, with the usual staining methods, the T or B nature of cells, thus, in case of tumor suspect, other techniques must be applied and, therefore, the patient must be otherwise considered. In this order, immunocytochemistry, cytofluorimetry or Polimerase Chain Reaction for antigen receptor rearrangement (PARR) could represent further methods to consider beside the cytology to differentiate a reactive lymphocyte population from a neoplastic one especially when a malignancy is suspected [36].…”