Salivary gland lymphoproliferative disorders: a Canadian tertiary center experience

Current evidence on diagnosis and treatment of parotid gland lymphomas: a systematic review

BACKGROUND AND PURPOSE

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.

Thymic Hyperplasia with Lymphoepithelial Sialadenitis (LESA)-Like Features: Strong Association with Lymphomas and Non-Myasthenic Autoimmune Diseases

Thymic hyperplasia (TH) with lymphoepithelial sialadenitis (LESA)-like features (LESA-like TH) has been described as a tumor-like, benign proliferation of thymic epithelial cells and lymphoid follicles. We aimed to determine the frequency of lymphoma and autoimmunity in LESA-like TH and performed retrospective analysis of cases with LESA-like TH and/or thymic MALT-lymphoma. Among 36 patients (21 males) with LESA-like TH (age 52 years, 32-80; lesion diameter 7.0 cm, 1-14.5; median, range), five (14%) showed associated lymphomas, including four (11%) thymic MALT lymphomas and one (3%) diffuse large B-cell lymphoma. One additional case showed a clonal B-cell-receptor rearrangement without evidence of lymphoma. Twelve (33%) patients (7 women) suffered from partially overlapping autoimmune diseases: systemic lupus erythematosus (n = 4, 11%), rheumatoid arthritis (n = 3, 8%), myasthenia gravis (n = 2, 6%), asthma (n = 2, 6%), scleroderma, Sjögren syndrome, pure red cell aplasia, Grave's disease and anti-IgLON5 syndrome (each n = 1, 3%). Among 11 primary thymic MALT lymphomas, remnants of LESA-like TH were found in two cases (18%). In summary, LESA-like TH shows a striking association with autoimmunity and predisposes to lymphomas. Thus, a hematologic and rheumatologic workup should become standard in patients diagnosed with LESA-like TH. Radiologists and clinicians should be aware of LESA-like TH as a differential diagnosis for mediastinal mass lesions in patients with autoimmune diseases.

Cancers of the Major Salivary Gland

Salivary gland malignancies are rare tumors that comprise multiple histologic entities with diverse clinical behavior. Mucoepidermoid carcinoma is the most frequent primary salivary malignancy, followed by adenoid cystic and acinic cell carcinoma. Although most salivary malignancies are asymptomatic, presentation with a rapidly enlarging mass may be accompanied by pain, functional neurologic deficits, soft-tissue invasion, or nodal enlargement. Assessment of clinical behavior and physical exam greatly contributes to diagnostic workup. Preoperative imaging, to include ultrasound, computed tomography, or magnetic resonance imaging, may assist with surgical planning. Limitations of preoperative fine-needle aspiration cytology mean that, in some cases, definitive histologic diagnosis may not be established until therapeutic surgery is undertaken. Treatment strategies rely on oncologic resection of the primary site with negative margins as well as adjuvant radiotherapy in patients with high-risk features, such as high-grade histology, advanced T class, or perineural invasion. Regional lymphadenectomy is recommended for involved nodal basins. Patients with clinically node-negative disease at high risk for occult nodal metastases may be considered for elective lymphadenectomy or radiotherapy. Use of chemotherapy in the adjuvant setting, in combination with radiotherapy, remains controversial. The rate of objective response to palliative chemotherapy in recurrent or metastatic salivary gland malignancy remains low. In studies that include a significant proportion of adenoid cystic carcinomas, whether disease stability represents an indolent disease process or the true effect of a therapeutic drug may be difficult to discern. Recognition of genetic alterations and protein expression unique to salivary malignancies presents exciting new opportunities for molecularly targeted therapy, although the response to molecularly targeted therapy in studies has been modest thus far.

Immunohistochemical Reappraisal Regarding the Frequency of Primary Salivary Gland Follicular Lymphoma

Although it has been described that extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphomas) are the most common type among primary salivary gland lymphomas (SGLs), some studies revealed that the frequency of follicular lymphomas (FLs) was as high as that of MALT lymphomas. However, it has been reported that many of these FLs may have developed in lymph nodes attached to the capsule of the glands or intraglandular lymph nodes. Clinical, histological, immunohistochemical, and cytogenetic features of 11 SGL cases, which were extracted from our surgical pathology file consisting of consecutive pathology cases, were reevaluated to further characterize whether they were actually primary SGLs. There were 3 (27%) cases of FLs, 5 (46%) cases of MALT lymphomas, and 3 (27%) cases of diffuse large B-cell lymphomas. Although all of our FL cases fulfilled the criteria of primary SGL, tumors of several FL cases were surrounded by podoplanin (by D2-40)-positive elongated vessels or linear structures indicative of nodal subcapsular sinuses (open or remnant). This finding would support the aforementioned possibility, and podoplanin staining is necessary before concluding that a FL is a primary SGL.

Classical Hodgkin lymphoma arising from heterotopic Warthin's tumor in the cervical lymph node: A case report

Heterotopic Warthin's tumor (WT) arising from the cervical lymph nodes is uncommon and WT presenting concomitantly with classical Hodgkin's lymphoma has only been previously reported three times in English literature. The current study presents an unusual case of classical Hodgkin lymphoma (CHL) involving the heterotopic WT in a 59-year-old male. Histopathologic examination revealied a WT with extensive expansion of mixed-cellularity CHL in a lymph node in the right of the neck. Clinical staging was determined as stage IA disease. The patient received four courses of chemotherapy and local consolidative radiotherapy, no evidence of disseminated lymphoma was observed over the 6-month follow-up. To the best of our knowledge, this is the first well documented collision tumor between CHL and heterotopic WT of the cervical lymph nodes. The present case also expands the anatomical site of malignant lymphomas associated with WT.

Treatment of Parotid Non-Hodgkin Lymphoma: A Meta-Analysis

Purpose

This meta-analysis aimed to review the published outcomes of parotid non-Hodgkin lymphoma (NHL) pertaining to different treatment modalities.

Materials and Methods

A total of 48 journal articles published between 1993 and 2015, comprising 742 cases of parotid NHL, were initially evaluated. In total, 108 patients from 12 studies who had sufficient data for analysis, including age, tumor histopathology, treatment modality, and outcome at final follow-up, were included. Patients were randomly assigned to different categories on the basis of histopathology and treatment modality. Groups were compared using Kaplan-Meier survival curve analysis and the Mann-Whitney U test.

Results

Log-rank tests demonstrated that for early-stage (I and II) parotid NHL of all histopathology variants, radiation therapy significantly improved the survival rate versus chemotherapy (P = .043), as well as combined treatment with chemotherapy and radiation therapy (P = .023). For early-stage diffuse large B-cell lymphoma, combined treatment significantly improved survival versus single treatment (P = .028). No treatment was received by seven patients with early-stage mucosa-associated lymphoid tissue lymphoma after undergoing parotidectomy. When the clinical outcomes of these patients were compared with those of other patients with the same histology who underwent further treatment, no significant differences were noted in survival outcomes.

Conclusion

Radiation therapy seems to be a valid treatment of early-stage parotid NHL. However, for diffuse large B-cell lymphoma, survival was higher with combined treatment versus single treatment. For early-stage parotid mucosa-associated lymphoid tissue lymphoma, complete excision of the tumor through superficial parotidectomy may have similar survival outcome.

Nodular Lymphocyte-Predominant Hodgkin Lymphoma in a Warthin Tumor of the Parotid Gland: A Case Report and Literature Review

Hodgkin lymphoma (HL) associated with Warthin tumor (WT) is extremely rare, accounting for only 3 cases of classical HLs. Here, we report for the first time the occurrence of a nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) involving the lymphoid stroma of a WT of the parotid gland. Pathogenesis of WT is controversial, with both a nodal and a parenchymal possible origin. On the other hand, extranodal involvement by HLs is uncommon. In our case, the coexistence of a WT and of a NLPHL within its stroma and in cervical lymph node emphasizes the importance of a careful evaluation of the lymphoid tissue in WT in order to exclude the possibility of an associated lymphoid malignancy.

Cancers of major salivary glands

Major salivary gland malignancies are a rare but histologically diverse group of entities. Establishing the diagnosis of a malignant salivary neoplasm may be challenging because of the often minimally symptomatic nature of the disease, and limitations of imaging modalities and cytology. Treatment is centered on surgical therapy and adjuvant radiation in selected scenarios. Systemic therapy with chemotherapeutic agents and monoclonal antibodies lacks evidence in support of its routine use.

Intraparotid classical and nodular lymphocyte-predominant Hodgkin lymphoma: pattern analysis with emphasis on associated lymphadenoma-like proliferations

Most of the lymphoproliferative diseases involving the salivary glands represent indolent non-Hodgkin B-cell lymphoma (marginal zone lymphoma) related to chronic autoimmune sialadenitis (Sjögren disease). Other types of non-Hodgkin lymphomas involve the salivary glands less frequently. On rare occasions, classical Hodgkin lymphoma (CHL) and nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) present initially as a primary salivary gland mass. We analyzed a series of CHL (n=3) and NLPHL (n=6) presenting initially as parotid gland tumors concerning their pattern (parenchymal vs. intraparotid lymph node) and the presence of salivary inclusions and epithelial proliferations within the lymphoma infiltrate. The pattern of infiltration was determined on hematoxylin and eosin-stained slides assisted by immunostaining for pancytokeratin to highlight lobular salivary gland parenchyma. Patients included 6 male and 3 female individuals with a mean age of 62 years (range, 36 to 88 y). Lymphoma was localized within intraparotid lymph nodes in 8 cases and was limited to salivary parenchyma in 1 case. Parenchymal involvement in nodal-based cases was scored as absent (3) or minimal (5). Salivary inclusions (acini and ductules) within affected lymph nodes were noted in 6 cases (4/5 NLPHLs and 2/3 CHLs). In 3/6 NLPHL cases, salivary inclusions showed variable proliferative changes ranging from prominent lymphoepithelial lesions to cystic and oncocytic (Warthin-like) epithelial changes. Scanty small lymphoepithelial lesions were seen in 1 of the 3 CHL cases. One NLPHL in the intraparotid lymph node was accompanied by prominent lymphoepithelial sialadenitis in the absence of clinical signs of Sjögren disease. This study highlights that a majority of parotid gland Hodgkin lymphomas arise within intraparotid lymph nodes. Frequent entrapment and proliferation of salivary ducts and acini within the lymphoma infiltrate might mimic a variety of benign lymphoepithelial mass-forming lesions (nonsebaceous lymphadenoma, Warthin tumor, and autoimmune sialadenitis). Pancytokeratin stain is helpful for reliable assessment of the background architecture.

Parotid gland follicular lymphoma lacking both cytoplasmic and surface light chains: a rare case

Immunoglobulin light chain (LC) restriction is detected in the majority of B-cell non-Hodgkin lymphoma (B-NHL) by flow cytometric immunophenotyping (FCI) and serves as a surrogate marker of monoclonality. Even though it is known a small percentage of mature B-NHLs lacking surface LC, deficiency of both cytoplasmic and surface LCs has been reported in only three B-NHL cases. We report a primary parotid gland follicular lymphoma in a 63-year-old man and the lymphoma cells were deficient of cytoplasmic/surface LCs. Compared to previous reports, we used a more sensitive FCI method by combining both monoclonal and polyclonal anti-LC antibodies. Lacking LCs poses as a pitfall for the initial diagnosis of B-NHL, as well as for detecting minimal residual disease. It is important to be aware of this rare immunophenotypic aberrancy.