Primary oral mucosa-associated lymphoid tissue (MALT) lymphoma in patient with monoclonale gammopathy: a rare case report

Abstract

Background: Monoclonal gammopathy is a biological reality encountered in approximately 1% of the general population. In the absence of clinical and biological signs, it is considered of undetermined significance; however, it can be a biological signature of a monoclonal lymphocytic or plasma-cell proliferation. Their localisation to the oral mucosa remains rare and difficult to diagnose, particularly in indolent forms that escape imaging techniques.

Case presentation: Here, we report the case of a 73-year-old woman with a history of IgM kappa gammopathy followed for 13 years. The patient did not have a chronic infection or an autoimmune disease, and all the biological investigations and radiological explorations were unremarkable during this period. The discovery of a submucosal nodule in the cheek led to the diagnosis of MALT lymphoma and regression of half of the IgM kappa level after resection. The review of the literature shows the dominance of clinical signs (i.e., a mass or swelling) in the diagnosis of primary MALT lymphomas of the oral cavity after surgical resection.

Conclusions: Our case illustrates the role of examination of the oral cavity in the context of a monoclonal gammopathy. The absence of clinical and radiological evidence in favor of lymphoplasmacytic proliferation, does not exclude a primary indolent MALT lymphoma of the oral mucosa.

Keywords: Extra nodal; Haemopathy; Head and neck; Light chain; Lymphoma; Monoclonal gammopathy; Mucosa-associated lymphoid tissue (MALT); Oral mucosa.

Fig. 1

Panoramic radiography at the first consultation negative for pathological bone imaging

Fig. 2

Intraoral view of submucosal nodule of the right check

Fig. 3

A and B Light examination of tumour, low magnification (haematoxylin and eosin stain, original magnification × 20), A Pseudo-nodular architecture of the excised lesion with some colonised lymphoid follicles with widened mantle zone in the MALT lymphoma, B Massive colonisation of the neoplastic follicles; tumour cells are scattered and infiltrate adjacent cellulo-adipose tissue with insheathing of the small nervous fillets (yellow arrow), but do not invade the healthy lobule of salivary gland (black arrow). No epithelial or salivary structure is observed in the tumour infiltrate, C Tumour cells of small size with an abundant and pale cytoplasm and irregular nuclei; these cells have rather dense chromatin nuclei with a cytoplasm sometimes off-centred and a plasma-cell differentiation (original magnification × 40). D, E Immunohistochemical staining (original magnification × 40), D Strong positive for CD20, E Strong positive for CD79a. F Uniform strong staining of membrane cells for IgM (original magnification × 20). G, H In situ hybridisation for light chain of immunoglobulin (original magnification × 40) G High expression of kappa light chain H Absence of the expression of lambda light chain