Low grade marginal zone B-cell lymphoma presenting as local amyloidosis in a submandibular salivary gland

Abstract

An unusual case of a low grade marginal zone B-cell lymphoma is reported and the literature reviewed. This case demonstrates that a diagnosis of lymphoma must be considered when there is amyloidosis in an otherwise asymptomatic submandibular salivary gland mass.

Many aetiologies are associated with submandibular salivary gland masses. Although rare, both extra nodal marginal zone B-cell lymphomas (MZBL) and amyloidomas of major salivary glands have been described as separate entities in the literature and are often associated with underlying disease . There have been no reported cases of MZBL presenting as amyloidosis occurring within a major salivary gland in an otherwise well patient. Such a case is described.

Case report

A 73-year-old woman was referred by her general practitioner (GP) regarding a mass within the left submandibular triangle of her neck.

The GP had arranged an ultrasound scan of the mass and a fine needle aspirate for cytology. The ultrasound scan suggested that the appearance was that of an ‘inflammatory pseudotumour of the left submandibular gland, but that adenoid cystic carcinoma could not be excluded’. The cytological appearances were reported as ‘unusual, in keeping with an inflammatory process but with no evidence of malignant cells’.

At her initial consultation, the patient gave a 3-month history of a mass in the left neck that had remained unchanged and which was otherwise asymptomatic. She denied recent weight loss, night sweats, fatigue or pruritus. She denied any history of a dry mouth or symptoms of sialadenitis. Medically she was fit and well. Her hypertension was controlled with bendroflumethiazide and captopril.

Clinical examination revealed a firm, non-tender, non-pulsatile, non-fluctuant 2.5 cm diameter mass within the left submandibular salivary gland. It was not fixed to the overlying skin. There was no cervical lymphadenopathy. A repeat fine needle aspirate for cytology was undertaken, the findings remained largely unchanged from the previous result and were not diagnostic. In view of the above, the patient was advised to have the gland removed for a definitive histological diagnosis.

The gland was excised uneventfully under general anaesthesia and the specimen sent for histological examination. Macroscopically, the specimen was a roughly ovoid nodular light brown tissue measuring 40 × 20 mm of unremarkable salivary gland tissue with the exception of a diffusely pale grey, ill-defined lesion measuring 15 × 10 mm. Microscopically, sections of the nodule showed massive amyloid deposition associated with a striking giant cell response. This was surrounded by a lymphocytic and plasma cell inflammatory response ( Fig. 1 ). The background submandibular gland also showed lymphoid hyperplasia with germinal centres, but these lymphoid aggregates were not confluent and no solid nodule of lymphoid tissue was seen.

Fig. 1
Amyloid deposition (continuous arrow) with giant cell response (two arrows) and plasma cell inflammation (dotted arrow) within the submandibular salivary gland. Haematoxylin–eosin stain; magnification ×5.

The presence of amyloid was confirmed by Congo Red dye which was strongly positive showing apple-green birefringence under polarized light ( Fig. 2 ). The amyloid appeared to be confined to the submandibular gland, which raised the possibility of a lymphoproliferative process. The specimen was sent for a second opinion and immunohistochemical analysis.

Fig. 2
Amyloid deposition confirmed by apple-green birefringence (continuous arrow) under polarized light. Obvious uptake of Congo Red dye (dotted arrow). Congo Red dye stain; magnification ×20.

The supplementary report showed that scattered within and around the amyloid deposition, was an infiltration of small monomorphic, monocytoid lymphocytes admixed with numerous plasma cells, which showed strong lambda restriction. Immunohistochemistry showed these lymphoid cells to be CD20 and CD79a positive. CD79a also highlighted the plasma cells, which were BCL2 positive and CD5 negative.

The histological features were those of a localized tumour forming amyloidosis with an underlying lymphoproliferative process in keeping with a low grade extra nodal marginal zone B-cell lymphoma.

Following this histological diagnosis, the patient was referred to the Haematology–Oncology Multidisciplinary Team. Further haematological and radiological investigations have been normal and as a result, no active treatment has been undertaken although the patient remains on long term review. Two years later she remains well.

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Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Low grade marginal zone B-cell lymphoma presenting as local amyloidosis in a submandibular salivary gland
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