OBJECTIVE: Parotid gland lymphoma (PGL) is a rare and challenging diagnosis. Different lymphomas can develop in the parotid gland, with the most common being the mucosa-associated lymphoid tissue (MALT) lymphoma, which originates directly from the glandular parenchyma. Other histologic subtypes arise from both intraglandular and extraglandular parotid lymph nodes. A consensus on diagnosis and treatment of PGL is still lacking, and published data is scarce and heterogeneous.
METHODS: We performed a systematic review of the literature, including studies published after 2001, when the WHO classification of lymphoid tumours was introduced.
RESULTS: Twenty retrospective studies were included in the analyses, eight of which focused exclusively on MALT lymphomas. Final analysis included 612 cases of PGL, with a 1.68:1 F/M ratio. MALT lymphoma was the most common histology, followed by follicular and diffuse large B-cell lymphoma. Most cases were low stages (IE/IIE acc. Ann Arbour, 76.5%) and only 10% of patients presented with symptoms, most commonly pain (4.8%) and B symptoms (2.2%). A high prevalence of associated autoimmune diseases was found, particularly Sjögren\'s syndrome, that affected up to 70% of patients with MALT lymphoma. In most cases diagnosis was achieved through parotidectomy (57.5%), or open biopsy (31.2%). Treatment strategies were either surgical, non-surgical or a combination of modalities. Surgery as a single-modality treatment was reported in about 20% of patients, supposing it might be a valuable option for selected patients.
CONCLUSIONS: Our review showed that the diagnosis and treatment of PGLs is far from being standardized and needs further, more homogeneous reports to reach consensus.

Lymphomas usually involve lymph nodes and other lymphoid tissues, but sometimes occur in non-lymphoid organs, called extra-nodal sites. Primary diffuse extra-lymph node large B-cell lymphoma (DLBCL) of the thyroid and parotid gland have been observed rarely. According to the most accredited guidelines, primary extra-nodal DLBCL of the parotid and thyroid glands should be treated with three cycles of R-CHOP followed by radiotherapy of the involved site (ISRT). Surgery alone is not enough to treat DLBCL. We describe two unusual cases of primary extra-nodal DLBCL in elderly patients treated exclusively with surgical resection, given the inability to apply chemotherapy. Both patients achieved clinical recovery, which was maintained after a follow-up of more than 18 months, despite not having performed the indicated chemotherapy protocol. The two cases presented here, and a few others reported in the literature, should be considered exceptions to the rule, and do not allow the conclusion that surgery alone might be sufficient for complete remission.