Specific location of ocular adnexal lymphoma and mortality: an international multicentre retrospective study.

AIMS: To examine whether the specific location of ocular adnexal lymphoma (OAL) and the American Joint Committee on Cancer (AJCC) TNM tumour stage are prognostic factors for mortality in the main OAL subtypes. METHODS: Clinical and survival data were retrospectively collected from seven international eye cancer centres. All patients from 1980 to 2017 with histologically verified primary or secondary OAL were included. Cox regression was used to compare the ocular adnexal tumour locations on all-cause mortality and disease-specific mortality. RESULTS: OAL was identified in 1168 patients. The most frequent lymphoma subtypes were extranodal marginal zone B-cell lymphoma (EMZL) (n=688, 59%); follicular lymphoma (FL) (n=150, 13%); diffuse large B-cell lymphoma (DLBCL) (n=131, 11%); and mantle cell lymphoma (MCL) (n=89, 8%). AJCC/TNM tumour-stage (T-stage) was significantly associated with disease-specific mortality in primary ocular adnexal EMZL and increased through T-categories from T1 to T3 disease. No associations between AJCC/TNM T-stage and mortality were found in primary ocular adnexal FL, DLBCL, or MCL. EMZL located in the eyelid had a significantly increased disease-specific mortality compared with orbital and conjunctival EMZL, in both primary EMZL and the full EMZL cohort. In DLBCL, eyelid location had a significantly higher disease-specific mortality compared with an orbital or lacrimal gland location. CONCLUSION: Disease-specific mortality is associated with AJCC/TNM T-stage in primary ocular adnexal EMZL patients. Lymphoma of the eyelid has the highest disease-specific mortality in primary EMZL, and in the full cohort of EMZL and DLBCL patients.

Chromosome Translocations, Gene Fusions, and Their Molecular Consequences in Pleomorphic Salivary Gland Adenomas.

Salivary gland tumors are a heterogeneous group of tumors originating from the major and minor salivary glands. The pleomorphic adenoma (PA), which is the most common subtype, is a benign lesion showing a remarkable morphologic diversity and that, upon recurrence or malignant transformation, can cause significant clinical problems. Cytogenetic studies of >500 PAs have revealed a complex and recurrent pattern of chromosome rearrangements. In this review, we discuss the specificity and frequency of these rearrangements and their molecular/clinical consequences. The genomic hallmark of PA is translocations with breakpoints in 8q12 and 12q13-15 resulting in gene fusions involving the transcription factor genes PLAG1 and HMGA2. Until recently, the association between these two oncogenic drivers was obscure. Studies of the Silver−Russel syndrome, a growth retardation condition infrequently caused by mutations in IGF2/HMGA2/PLAG1, have provided new clues to the understanding of the molecular pathogenesis of PA. These studies have demonstrated that HMGA2 is an upstream regulator of PLAG1 and that HMGA2 regulates the expression of IGF2 via PLAG1. This provides a novel explanation for the 8q12/12q13-15 aberrations in PA and identifies IGF2 as a major oncogenic driver and therapeutic target in PA. These studies have important diagnostic and therapeutic implications for patients with PA.

Vaginal melanoma in Denmark from 1980 to 2018: A population-based study based on genetic profile and survival.

OBJECTIVE: To investigate the clinical, pathological, and genetic characteristics of patients with vaginal melanoma in a nationwide setting. MATERIALS/METHODS: All patients diagnosed with vaginal melanoma from 1980 to 2018 were collected by searching the digital archives of the Danish Registry of Pathology (Patobank). Patient specimens were examined, the histological diagnoses were validated, and targeted next-generation sequencing (NGS) of known frequent hot spots in 163 genes was performed. RESULTS: Fifty-two patients were included. The incidence for primary melanoma of the vagina in the Danish population (5.5 million people) was calculated to be 0.24 cases/million/year from 1980 to 2018. For all patients, the median OS was 17.5 months (95% CI: 13.0-24.0), and the 5-year OS was 19.4% (95% CI: 10.9-34.3). We identified frequent mutations in ATRX (7/25 cases) and TP53 (7/25 cases). Mutations found in TP53 were associated with a significant decrease in OS (p = 0.043), whereas mutations in the ATRX gene alone did not show a significant impact on OS (p = 0.3649). Patients who harbored co-mutations in both ATRX and TP53 showed a significant reduction in OS (p = 0.0081), with a median OS of 9.5 months compared to 20 months in those without the co-mutation. CONCLUSIONS: Vaginal melanoma is a rare disease with a poor prognosis presumably due to vague symptoms and the anatomical location of the disease. Co-mutations in ATRX and TP53 and mutations in TP53 alone were associated with a poor prognosis, and these genes are potentially interesting targets for future therapy.

Trends in the Management of Non-Vestibular Skull Base and Intracranial Schwannomas.

The aim of this review is to analyze the latest trends in the management of non-vestibular skull base and intracranial schwannomas in order to optimize tumor control and quality of life. Non-vestibular cranial nerve schwannomas are rare lesions, representing 5-10% of cranial nerve schwannomas. Management decisions should be individualized depending on tumor size, location and associated functional deficits. Generally, large sized schwannomas exerting significant mass effect with increased intracranial pressure are treated surgically. In some cases, even after optimal skull base resection, it is not possible to achieve a gross total resection because tumor location and extent and/or to reduce morbidity. Thus, subtotal resection followed by stereotactic radiosurgery or fractioned radiotherapy offers an alternative approach. In certain cases, stereotactic radiosurgery or radiotherapy alone achieves good tumor control rates and less morbidity to gross total resection. Finally, given the slow growth rate of most of these tumors, observation with periodic radiographic follow-up approach is also a reasonable alternative for small tumors with few, if any, symptoms.

Ultraviolet radiation drives mutations in a subset of mucosal melanomas.

Although identified as the key environmental driver of common cutaneous melanoma, the role of ultraviolet radiation (UVR)-induced DNA damage in mucosal melanoma is poorly defined. We analyze 10 mucosal melanomas of conjunctival origin by whole genome sequencing and our data shows a predominance of UVR-associated single base substitution signature 7 (SBS7) in the majority of the samples. Our data shows mucosal melanomas with SBS7 dominance have similar genomic patterns to cutaneous melanomas and therefore this subset should not be excluded from treatments currently used for common cutaneous melanoma.

Ocular adnexal lymphoma in Denmark: a nationwide study of 387 cases from 1980 to 2017.

BACKGROUND: Nationwide studies of ocular adnexal lymphoma (OAL) are very rare in the literature, and knowledge on incidence, subtype distribution and long-term survival data is limited. This is the largest national study of OAL to date. This study sought to find information on incidence, changes in incidence, clinical findings, distribution of subtypes, survival and prognostic factors. METHODS: Patients diagnosed with OAL from January 1, 1980 to December 31, 2017 were identified in Danish registers, and clinical as well as survival data were collected. The data were analysed with Kaplan-Meier plots and log-rank test. RESULTS: 387 patients were included in the study. The major lymphoma subtypes were extranodal marginal-zone B cell lymphoma (EMZL) (55%), diffuse large B cell lymphoma (DLBCL) (13%), mantle cell lymphoma (MCL) (11%) and follicular lymphoma (FL) (10%). OAL is a disease of the elderly (median age 69 years). The incidence of lymphoma of the ocular adnexal region has increased significantly throughout the time period of the study (Pearson correlation coefficient, r=0.65; P<0.001). In the period 1980-1984, the incidence was 0.086 per 100 000, which increased to 0.307 per 100 000 in the period 2013-2017. Low-grade, low-stage primary lymphomas were treated with radiotherapy, whereas patients with high-stage, high-grade and/or relapsed disease were treated with chemotherapy. Low-grade subtypes EMZL (89%) and FL (56%) had better 10-year disease-specific survival than the high-grade lymphomas DLBCL (38%) and MCL (31%)(p<0.001). CONCLUSION: OAL is increasing in incidence in the Danish population for unknown reasons. However, the prognosis for most OAL is favourable, as highlighted in this national long-term study.

The molecular profile of mucosal melanoma.

Herein, we wanted to explore the molecular landscape of mucosal melanoma from different sites and identify potential molecular targets for future therapy. Mucosal melanomas (N = 40) from different sites (conjunctiva, sinonasal cavity, rectum, and vagina) were investigated. Targeted next-generation sequencing along with Nanostring gene expression profiling was performed. Genetically, conjunctival melanoma was characterized by BRAF-V600E (30%) and NF1 mutations (17%). Mucosal melanomas at nonsun-exposed sites harbored alterations in NRAS, KIT, NF1, along with atypical BRAF mutations. When comparing the gene expression profile of conjunctival melanoma and nonsun-exposed mucosal melanoma, 41 genes were found to be significantly deregulated. Programmed death-ligand 1 (PD-L1) presented a significant sixfold upregulation in conjunctival melanoma compared to the other mucosal melanomas. While melanomas of the sinonasal cavity, vagina, and rectum are molecularly similar, conjunctival melanoma is characterized by a higher frequency of BRAF-V600E mutations and differential expression of several genes involved in the immune response.

Lymphoma of the Lacrimal Gland - An International Multicenter Retrospective Study.

PURPOSE: To characterize the clinical features of subtype-specific lacrimal gland lymphoma and their effect on patient survival. DESIGN: Multicenter retrospective interventional case series. METHODS: Patient data were collected from 6 international eye cancer centers from January 1, 1980, through December 31, 2017. All patients with histologically verified primary or secondary lymphoma of the lacrimal gland were included. Primary endpoints were overall survival (OS) and disease-specific survival (DSS). RESULTS: A total of 260 patients with lacrimal gland lymphoma were identified. The median age was 58 years and 52% of patients were men. Non-Hodgkin B-cell lymphomas constituted 99% (n = 258) and T-cell lymphomas constituted 1% (n = 2). The most frequent lymphoma subtypes were extranodal marginal zone B-cell lymphoma (EMZL) (n = 177, 68%), follicular lymphoma (FL) (n = 26, 10%), diffuse large B-cell lymphoma (DLBCL) (n = 25, 10%), and mantle cell lymphoma (MCL) (n = 17, 7%). Low-grade lymphomas (EMZL and FL) were most commonly treated with external beam radiotherapy (EBRT), whereas high-grade lymphomas (DLBCL and MCL) were treated with chemotherapy in combination with rituximab and/or EBRT. The prognosis was relatively good with a 5-year OS and DSS of 73.8% and 87.5%, respectively. Lymphoma subtype was a statistically significant predictor for DSS, with EMZL (5-year DSS: 93.4%) having the best prognosis and DLBCL (5-year DSS: 52.6%) having the poorest. CONCLUSIONS: This is the largest reported collection of data of subtype-specific lacrimal gland lymphoma. The subtype distribution of lacrimal gland lymphoma resembles that of the ocular adnexa. Prognosis is good and the histologic subtype is a significant predictor for disease-specific survival.

Gamma Knife Radiosurgery for Uveal Melanoma: A Retrospective Review of Clinical Complications in a Tertiary Referral Center.

INTRODUCTION: Gamma knife radiosurgery (GKR) has shown promising results in the treatment of intraocular uveal melanoma (UM) in terms of local tumor control. However, GKR is not free from potentially sight-threatening side effects, including cataract, dry eye disease, vitreous hemorrhage, radiation retinopathy (RR), radiation maculopathy (RM), optic neuropathy, and neovascular glaucoma. The aim of this paper is to report our 20-year experience in UM management with GKR focusing on the rate of clinical treatment-induced complications. METHODS: Single-center, retrospective, observational study, including all patients with UM treated at the Ocular Oncology and Uveitis Service, in the Department of Ophthalmology of the San Raffaele Scientific Institute, Milan from September 1993 to September 2018. Clinical charts comprised complete ophthalmological examination with measurement of best-corrected visual acuity, slit-lamp biomicroscopy, intraocular pressure measurement, gonioscopy, and indirect ophthalmoscopy at each visit. B-scan ultrasound (Aviso S, 10 MHz probe; Paris, France), optical coherence tomography (Heidelberg Spectralis; Heidelberg Engineering, Heidelberg, Germany), retinography, and fundus fluorescein angiography (standard or ultra-widefield [UWF; California, Optos, Dunfermline, Scotland, UK]) were performed aiding in the diagnosis of complications. RESULTS: Overall, 194 patients (100 males, 51.6%) were reviewed. The median age at the time of the treatment was 65 years (range 27-89) and all participants were Caucasian. In 185 eyes (95.4%), the tumor was primarily located at the choroid. The median follow-up was 57.6 months; radiation-induced complications were found in 145 eyes (74.7%). Radiation-induced cataract and RR were the most frequent events, with a relative incidence of 41.2 and 34.5%, respectively, followed by neovascular glaucoma (27.3%), optic neuropathy (18.6%), RM (11.4%), vitreous hemorrhage (14.4%), phthisis bulbi (7.7%), hyphema (0.5%), and corneal melting (0.5%). The shorter onset of side effects involved the optic nerve (median 14.9 months) and the macula (median 13.7 months). CONCLUSION: Despite modern and advanced strategies introduced to limit GKR side effects, cataract and RR still represent a serious limitation of this treatment. Incidence of RR was higher in our cohort compared to other reports, probably due to increased diagnosis rate permitted by UWF retinal imaging.

Lymphoplasmacytic lymphoma infiltrating both lacrimal glands in a patient with Waldenström's macroglobulinemia.

PURPOSE: To describe a case of Waldenström's macroglobulinemia/lymphoplasmacytic lymphoma with infiltration of both lacrimal glands. OBSERVATIONS: A 63-year-old male with Waldenström's macroglobulinemia was referred to the ophthalmological clinic due to intermittent bilateral painless swollen eyelids. The patient had slight bilateral chemosis along with swelling of both eyelids. A mechanical ptosis was present on both sides. Funduscopic examination and tonometry were normal. Computed tomography and positron emission tomography showed an enlargement of both lacrimal glands with positive PET signal, and hence a biopsy was performed for histological and cytogenetic examination. Histopathological examination revealed an infiltrate of lymphoplasmacytic cells and small lymphocytes within the lacrimal gland. The tumor cells stained positive for IgM and CD20, CD79, BCL-2, and kappa light chain. A cytogenetic examination revealed a mutation in MYD88 confirming Morbus Waldenström/lymphoplasmacytic lymphoma. CONCLUSIONS AND IMPORTANCE: Intermittent swollen lacrimal glands are a rather common symptom, and Morbus Waldenström/lymphoplasmacytic lymphoma should be considered as a differential diagnosis. This symptom should be carefully evaluated in Waldenström patients, as it can be a sign of disease progression in case of lacrimal gland involvement.

The role of infectious agents in cancer of the ocular region.

The purpose of the study was to investigate the association between infectious agents and the development of cancer in the ocular adnexa. A comprehensive literary study was carried out, reviewing and summarizing previous reports on the topic. A broad range of malignancies of the ocular adnexa are associated with infectious agents. A strong association and possible causal relationship between the infectious agent and the development of ocular adnexal cancer are seen in Merkel cell carcinoma (Merkel cell polyomavirus), Burkitt lymphoma (Epstein-Barr virus) and Kaposi sarcoma (human herpesvirus 8). Infection with Chlamydia psittaci has been associated with the development of extranodal marginal zone B-cell lymphoma in Italy. Human papillomavirus infection has been associated with the development of squamous cell carcinomas of the ocular adnexa, although with a highly variable reported prevalence. By exploring the role of infectious agents in the ocular adnexa and the mechanism by which they contribute to oncogenesis, the diagnostics, management and prevention of these malignancies may also improve. Antibiotic treatment and vaccines against infectious agents may be valuable in future treatment. Additionally, the presence of infectious agents within the tumours may have a prognostic or predictive value.

Periocular necrotizing soft tissue infection in Greater Copenhagen.

PURPOSE: Necrotizing soft tissue infection, also known as necrotizing fasciitis (NF), is a fast-spreading life-threatening infection that most commonly affects the lower limbs, groin, or abdomen. Periocular necrotizing fasciitis (PNF) is rare. Limited data exist on PNF immune cell subset; hence, this study aims to determine the representation of immune cell subsets in patients diagnosed with PNF using immunohistochemical stainings. METHODS: All patients diagnosed with PNF at Copenhagen University Hospital from 2008 to 2018 were included. Their electronic medical records and pathology reports were assessed, and available tissue specimens were reviewed and stained with monoclonal antibodies for CD1a+ Langerhans' cells, CD3+ T lymphocytes, CD15+ granulocytes, CD44+ lymphohematopoietic cells, CD68+ histiocytes, CD79α+ B lymphocytes, and FXIIIa+ dendritic macrophages and Langerhans' cells. The number of positive cells was counted, and an average score was calculated. The location of immune cells and bacteria was assessed. RESULTS: The specimens were characterized by acute inflammation and necrosis of the fascia, while striated muscle involvement was less frequent. Haemolytic group A streptococci and Staphylococcus aureus were identified and mainly located in the deep dermis and subcutis in close relation to the fascia. Only few areas harboured both bacteria and inflammatory cells. Granulocytes, histiocytes and CD44+ lymphohematopoietic cells were demonstrated to be abundant in all patients, while B and T lymphocytes, dendritic macrophages and Langerhans' cells were less frequent. CONCLUSION: The immune cell subsets found in this study of PNF were consistent with those identified in the literature on NF in other anatomical locations. This study concludes that immune cells are abundant and exhibit a typical pattern in PNF.

International multicentre retrospective cohort study of ocular adnexal marginal zone B-cell lymphoma.

BACKGROUNDS/AIMS: To date, this is the largest cohort study on extranodal marginal zone B-cell lymphoma (EMZL) of the ocular adnexa (OA). The aim of the study was to characterise the clinical features of OA-EMZL. METHODS: A retrospective multicentre study involving seven international eye cancer centres. Data were collected from 1 January 1980 through 31 December 2017. A total of 689 patients with OA-EMZL were included. RESULTS: The median follow-up time was 42 months. The median age was 62 years (range, 8-100 years), and 55 % (378/689 patients) of patients were women. The majority of patients (82%, 558/680 patients) were diagnosed with primary OA-EMZL with Ann Arbor stage IE (90%, 485/541 patients) and American Joint Committee on Cancer stage T2 (61%, 340/557 patients) at the time of diagnosis. The orbit (66%, 452/689 patients) and the conjunctiva (37%, 255/689 patients) were the most frequently involved anatomical structures. The 5-year, 10-year and 20-year disease-specific survival (DSS) were 96%, 91% and 90%, respectively. Stage IE patients treated with external beam radiation therapy (EBRT) as monotherapy (10-year DSS, 95%) were found to have a better DSS than stage IE patients treated with chemotherapy (10-year DSS, 86%). Stage IIIE/IVE patients treated with chemotherapy and rituximab had a better DSS (10-year DSS, 96%) than stage IIIE/IVE patients treated with chemotherapy without rituximab (10-year DSS, 63%). CONCLUSIONS AND RELEVANCE: EMZL is a slow-growing tumour with an excellent long-term survival. Low-dose EBRT as monotherapy should be considered in localised OA-EMZL. Rituximab-based chemotherapy should be chosen in those patients with disseminated disease.

High-throughput sequencing reveals no viral pathogens in eight cases of ocular adnexal extranodal marginal zone B-cell lymphoma.

The purpose of the present study was to perform a next-generation sequencing (NGS) based analysis of viruses in ocular adnexal extranodal marginal zone B-cell lymphoma (EMZL). Eight patients with extraocular EMZL were identified in the archives of Department of Ophthalmology, Copenhagen University Hospital. All cases were validated according to the World Health Organization classification. We subjected samples to enrichment of virion-associated (encapsidated) nucleic acids which included sample homogenization, filtration, and nuclease treatment. Both DNA and RNA were sequenced, and we analyzed the sequencing data for the presence of viral sequences. We detected no pathogenic viruses likely to be associated to development of EMZL. In one case, we detected human polyomavirus 7 and traces of Epstein-Barr virus (EBV) (human herpesvirus 4 (HHV4)) and a human papillomavirus. In conclusion, no viral pathogens were consistently detected in the extraocular EMZL samples when applying NGS-based methods.

Lymphomas of the head and neck region: an update.

The field of haematopathology is rapidly evolving and for the non-specialized pathologist receiving a specimen with the possibility of a lymphoid malignancy may be a daunting experience. The coincidence of the publication, in 2017, of the WHO monographies on head and neck and haematopoietic and lymphoid tumours prompted us to write this review. Although not substantially different from lymphomas elsewhere, lymphomas presenting in this region pose some specific problems and these are central to the review. In addition, differences in subtype frequency and morphological variations within the same entity are discussed. The difficulty in diagnosis related to some specimens led us to briefly mention common subtypes of systemic lymphomas presenting in the head and neck region.

An update on head and neck cancer: new entities and their histopathology, molecular background, treatment, and outcome.

The head and neck region harbor numerous specialized tissues of all lineages giving rise to a plethora of different malignancies. In recent years, new types and subtypes of cancer has been described here due to the recognition of their histological and molecular characteristics. Some have been formally accepted in the most recent classifications from the World Health Organization (WHO) and American Joint Committee on Cancer (AJCC) as distinct diseases due to characteristics in clinical presentation, outcome, and treatment. In particular, this applies to malignancies of the salivary gland, sinonasal tract, and oropharynx. In this overview, we present the most recent developments in the classification, histopathological characteristics, and molecular features of head and neck cancer. The clinical and radiological characteristics, outcome, and treatment options including perspectives for targeted therapies, are discussed.

Orbital precursor B-lymphoblastic lymphoma involving the extraocular muscles in a 56-year-old male and a review of the literature.

The aim of the present study was to describe a rare case of orbital precursor B-lymphoblastic lymphoma (B-LBL) in an adult. A 56-year-old male in complete remission of a gastric precursor B-LBL was referred to our orbital clinic due to rapid development of left-sided painless periorbital swelling, diplopia, and proptosis. Complete ophthalmoplegia was observed. Notably, magnetic resonance imaging showed swelling of the medial and inferior rectus muscles in the left orbit and biopsies were performed. Following histological diagnosis of precursor B-LBL, the patient was treated with radiotherapy (2Gy × 20) and chemotherapy according to the NOPHO ALL 2008 protocol. The disease progressed and the patient succumbed after 5 months. Histomorphologically, a lymphoblastic infiltrate was observed within the skeletal muscle tissue. The tumor cells were small and immature, and stained strongly for cluster of differentiating (CD)10, CD79a, paired box 5 and B cell lymphoma-2. The Ki-67 proliferative index was 90%. Multiplex ligation-dependent probe amplification and array comparative genomic hybridization detected whole chromosomal gain of X and 12, and both hemizygous and homozygous deletion on 9p comprising cyclin dependent kinase inhibitor 2A/B. Furthermore, array comparative genomic hybridization detected copy number imbalances consisting of focal or smaller deletions on chromosomes 1, 9, 10, 11 and 20. The final diagnosis was precursor B-LBL relapse in the extraocular muscles. Orbital precursor B-LBL is extremely rare in adults, and the diagnosis may be challenging to make. It is recommended to obtain material for cytogenetic and molecular analyses.

Orbital Lymphoma-An International Multicenter Retrospective Study.

PURPOSE: To investigate and characterize the clinical features of subtype-specific orbital lymphoma. DESIGN: Retrospective, interventional case series. METHODS: The study included 7 international eye cancer centers. Patient data were collected from January 1, 1980 through December 31, 2017. A total of 797 patients with a histologically verified orbital lymphoma were included. The primary endpoints were overall survival, disease-specific survival, and progression-free survival. RESULTS: The median age was 64 years, and 51% of patients (n = 407) were male. The majority of lymphomas were of B-cell origin (98%, n = 779). Extranodal marginal zone B-cell lymphoma (EMZL) was the most frequent subtype (57%, n = 452), followed by diffuse large B-cell lymphoma (DLBCL) (15%, n = 118), follicular lymphoma (FL) (11%, n = 91), and mantle cell lymphoma (MCL) (8%, n = 66). Localized Ann Arbor stage IE EMZL and FL were frequently treated with external beam radiation therapy. DLBCL, MCL, and disseminated EMZL and FL were primarily treated with chemotherapy. EMZL and FL patients had a markedly better prognosis (10-year disease-specific survival of 92% and 71%, respectively) than DLBCL and MCL patients (10-year disease-specific survival of 41% and 32%, respectively). CONCLUSIONS: Four lymphoma subtypes were primarily found in patients with orbital lymphoma: EMZL, DLBCL, FL, and MCL. The histologic subtype was found to be the main predictor for outcome, with EMZL and FL patients having a markedly better prognosis than DLBCL and MCL.

Salivary myoepithelial cells: an addendum.

Salivary myoepithelial cells bear particular appendages and are involved in processes that have received incomplete attention in previous reviews. Here, cilia on myoepithelial cells are reviewed as regards substructure, occurrence, detection (electron microscopy, double immunofluorescence together with confocal microscopy), and roles (sensory reception, evolutionary homology, paracrine interaction). Attention is drawn to regressive changes affecting those cells (e.g. accumulation of lipofuscin), possible alterations of their cytoskeleton, internalization of apoptotic bodies and haemosiderin, and role in salivary microcalcification. The ability of differentiated salivary myoepithelial cells to divide is re-examined, particularly its increase in chronic inflammation and under experimental conditions. Caution with regard to histogenetic models of salivary neoplasia is re-emphasized; methodological deficiencies and areas of controversy are outlined; and lines of future research are suggested.