Sebaceous Epithelial-Myoepithelial Carcinoma of the Salivary Gland: Clinicopathologic and Immunohistochemical Analysis of 6 Cases of a New Histologic Variant

Integrative Analysis of the Predictive Value of Perilipin Family on Clinical Significance, Prognosis and Immunotherapy of Glioma

Gliomas are common tumors of the central nervous system. The PLINs family is widely involved in the regulation of lipid metabolism and has been associated with the development and invasive metastasis of various malignancies. However, the biological role of the PLINs family in gliomas is still unclear. TIMER and UALCAN were used to assess PLINs mRNA expression in gliomas. “Survminer” and “Survival” were used to evaluate the connection between PLINs expression and glioma patients’ survival. cBioPortal was applied to assess PLINs’ genetic alterations in glioblastoma multiforme (GBM) and low-grade glioma (LGG). The correlation of PLINs expression with tumor immune cells was analyzed by TIMER. The expressions of PLIN1, PLIN4, and PLIN5 were decreased in GBM compared to normal tissues. However, PLIN2 and PLIN3 were significantly increased in GBM. Prognostic analysis showed that LGG patients with high PLIN1 expression had better overall survival (OS), and high expression of PLIN2/3/4/5 was associated with unfavorable OS. We further determined that the expression of PLINs members in gliomas was strongly related to tumor immune cells and immune checkpoint-associated genes. PLINS may be potential biomarkers for regulating the tumor microenvironment and predicting the efficacy of immunotherapy. In addition, we determined that PLIN1 may affect glioma patients’ therapeutic sensitivity to temozolomide. Our results demonstrated the biological significance and clinical values of PLINs in gliomas and provide a basis for future in-depth exploration of the specific mechanisms of each member of PLINs in gliomas.

A dog with extraskeletal osteosarcoma of the salivary glands survived long-term, following surgical resection and adjuvant therapy

A 12-year-old French bulldog presented with a mass on the right lower jaw. Computed tomography revealed that the mass originated from the salivary gland and was not continuous with the right mandible. The mass was surgically removed and subsequently diagnosed as extraskeletal osteosarcoma of the salivary gland following histopathological and immunohistochemical examinations. Although the surgical margin was clear, postoperative adjuvant therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) was initiated. Lung metastasis was observed 249 days after the initial examination; therefore, toceranib was initiated with NSAIDs. The dog died 496 days after the initial examination of this disease progression but had good long-term management with a combination of surgery, NSAIDs, and toceranib.

Epithelial-myoepithelial carcinoma of the nasopharynx: A case report and review of the literature

Background

Epithelial-myoepithelial carcinoma (EMCa) is a rare low-grade malignant tumor that most commonly occurs in the salivary glands, with approximately 320 cases having been reported worldwide. Here, we report the third case of EMCa occurring in the nasopharynx. Rare cases in the breast, pituitary gland, lacrimal gland, nose, paranasal sinus, nasal cavity, trachea and bronchus, lung, and even the pleura mediastinalis have also been reported. Histopathology and immunohistochemistry are useful for confirming the diagnosis of EMCa, which is characterized by biphasic tubular structures composed of inner ductal and outer clear myoepithelial cells and stains for different markers in each layer. However, because of the rarity of EMCa, the clinicopathological characteristics and treatment of these patients remain unclear.

Case presentation

We report a rare case of EMCa of the nasopharynx. A 51-year-old man presented with a 5-month history of pain while swallowing and aggravation accompanied by right ear tinnitus lasting for 1 month. Nasopharyngoscopy and magnetic resonance imaging (MRI) of the nasopharynx and neck revealed a 5.6 cm × 3.4 cm × 3.1 cm mass in the nasopharyngeal space, invasion of the right cavernous sinus, and lymph node enlargement in the right retropharyngeal space. On 17 April 2019, based on the histopathological and immunohistochemical features, a final diagnosis of EMCa of the right nasopharynx was made. The patient underwent concurrent chemoradiotherapy (CCRT), and his symptoms were relieved after treatment. On 10 January 2022, nasopharynx MRI and biopsy revealed local recurrence, but chest and abdominal computed tomography (CT) showed no obvious signs of metastasis. The local recurrence-free survival (LRFS) period was 33 months.

Conclusion

To the best of our knowledge, this is the third reported case of EMCa in the nasopharynx and the only case of EMCa in the nasopharynx treated with CCRT, and a partial response was achieved. Therefore, to improve the quality of life and prognosis of patients with unresectable tumors, we believe that CCRT is a suitable option. Further clinical observations are required to elucidate the pathophysiology and prognosis of EMCa.

Epithelial-myoepithelial carcinoma ex pleomorphic adenoma of the parotid gland with unique histologic differentiation: A rare case report

Epithelial myoepithelial carcinoma (EMC) is an uncommon low-to-intermediate grade salivary gland malignancy that accounts for 1% of all tumors arising in salivary glands. About 80% of these tumors affect the parotid gland. These lesions either arise de novo or from existing pleomorphic adenoma (PA). Histologically, these tumors reveal a biphasic cell population with inner ductal epithelial cells and peripheral myoepithelial cells. There are many histologic variants of EMC, but sebaceous, verocay-like differentiation and high-grade transformation is very rarely reported. This article describes a 48-year-old female patient diagnosed with EMC ex PA with unique histologic differentiation.

Epithelial-Myoepithelial Carcinoma of the Minor Salivary Glands: Case Series with Comprehensive Review

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor that is histologically characterized by biphasic tubular structures composed of inner ductal and outer clear myoepithelial cells, which is especially uncommon in the minor salivary glands (MSG). Because of its histologic variety, complexity, and heterogeneity, it is sometimes challenging to make the accurate diagnosis. Here, we report a literature review of EMC of the MSGs with our experience of two cases. Incisional biopsy was suggestive of pleomorphic adenoma in Case 1 and pleomorphic adenoma or a low-grade salivary gland carcinoma in Case 2. Both cases were performed intraoral tumor resection, and they have good postoperative courses and are alive with no evidence of local recurrence or metastasis at 31 and 16 months, respectively. Considering that the anatomy, structure, and size of salivary glands are quite different from MSGs, it might be difficult to predict EMCs of the MSG similarly to EMCs of the major salivary glands. This comprehensive review also reports the features of EMC of the MSG cases and the trends of diagnosis and discusses treatment strategy.

The Diagnostic Utility of RAS Q61R Mutation-specific Immunohistochemistry in Epithelial-Myoepithelial Carcinoma

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland cancer characterized by biphasic tubular structures composed of inner ductal and outer clear myoepithelial cells. Because of its histologic variety and overlap of histologic features with other salivary gland tumors, there are broad differential diagnoses. The HRAS Q61R mutation has been reported to be frequent in and specific to EMC. We evaluated the usefulness of RAS Q61R mutant-specific immunohistochemical (IHC) staining for detecting this genetic alteration in EMC. We investigated 83 EMC cases and 66 cases of salivary gland tumors with an EMC-like component, including pleomorphic adenoma, adenoid cystic carcinoma, basal cell adenoma/adenocarcinoma, and myoepithelial carcinoma. Sanger sequencing was performed for HRAS, KRAS, and NRAS. The diffuse and membranous/cytoplasmic RAS Q61R IHC expression was observed in 65% of EMC cases, in which all cases harbored the HRAS Q61R mutation. IHC-positive cases were present only in de novo EMCs (54/76 cases, 71%) but not in EMCs ex pleomorphic adenoma. The immunoreactivity was almost always restricted to the myoepithelial cells. Conversely, all EMC cases lacking the HRAS Q61R mutation were negative on IHC. In addition, only 3% of EMC-like tumors showed the abovementioned immunopositivity. None of the cases examined carried KRAS or NRAS mutations. IHC for RAS Q61R is highly sensitive and specific for detecting the HRAS Q61R mutation in EMC. Since significant immunopositivity was almost exclusively identified in nearly two thirds of EMCs but seldom in the histologic mimics, the IHC of RAS Q61R is a useful tool for diagnosing EMC in general pathology laboratories.

Epithelial-Myoepithelial Carcinoma

Epithelial-myoepithelial carcinoma is an uncommon low-grade salivary gland carcinoma. It is classically characterized by biphasic tubular structures composed of inner eosinophilic ductal cells and outer clear myoepithelial cells. In addition, epithelial-myoepithelial carcinoma sometimes shows various histologic features, including a cribriform pattern, basaloid appearance, and sebaceous differentiation. Because clear myoepithelial cells are also noted in other benign and malignant salivary gland tumors, the histologic variety and similarity with other tumor entities make the diagnosis of epithelial-myoepithelial carcinoma challenging. A recent analysis revealed that HRAS hotspot point mutations are specifically identified in epithelial-myoepithelial carcinoma and the assessment of given genes facilitate the correct diagnosis.

Sebaceous Epithelial-Myoepithelial Carcinoma With Aggressive Behavior and Evidence of Preexisting Pleomorphic Adenoma

Epithelial-myoepithelial carcinoma (EMCA) is a rare low-grade carcinoma of the salivary glands with multiple morphological variants. One such variant, sebaceous EMCA (SEMCA), has been reported in the literature. Distinguishing it from other tumors such as sebaceous carcinoma is crucial, as SEMCA typically behaves more indolently. We present a case of a SEMCA in the right parotid of a 71-year-old man that shows features of aggressive behavior such as facial nerve invasion and extraparenchymal extension. Also, we report evidence of preexisting pleomorphic adenoma within this tumor.

Ex vivo assessment of targeted therapies in a rare metastatic epithelial-myoepithelial carcinoma

Epithelial-myoepithelial carcinoma (EMC) is a rare subtype of salivary gland neoplasms. Since the initial description of the cancer, just over 300 cases have been reported. EMCs occupy a biphasic cellular differentiation-state defined by the constitution of two cell types representing epithelial and myoepithelial lineages, yet the functional consequence of the differentiation-state heterogeneity with respect to therapy resistance of the tumors remains unclear. The reported local recurrence rate of the cases is approximately 30%, and while distant metastases are rare, a significant fraction of these cases are reported to receive no survival benefit from radio- or chemotherapy given in addition to surgery. Moreover, no targeted therapies have been reported for these neoplasms. We report here the first use and application of ex vivo drug screening together with next generation sequencing to assess targeted treatment strategies for a rare metastatic epithelial-myoepithelial carcinoma. Results of the ex vivo drug screen demonstrate significant differential therapeutic sensitivity between the epithelial and myoepithelial intra-tumor cell lineages suggesting that differentiation-state heterogeneity within epithelial-myoepithelial carcinomas may present an outlet to partial therapeutic responses to targeted therapies including MEK and mTOR inhibitors. These results suggest that the intra-tumor lineage composition of EMC could be an important factor to be assessed when novel treatments are being evaluated for management of metastatic EMC.

Epithelial-myoepithelial carcinoma ex-pleomorphic adenoma of the parotid gland: report of a rare case with immunohistochemical and genetic analyses

Epithelial-myoepithelial carcinoma (EMCa) is a rare low-grade salivary malignancy. It is rare for EMCa to occur as the carcinomatous component of carcinoma ex-pleomorphic adenoma (PA). We examined one additional case of EMCa ex-PA, immunohistochemically and genetically. The patient was an 83-year-old female, who suffered from swelling of the right parotid region. Histologically, the tumor contained a hyalinized nodule, which displayed elastosis. The main tumor exhibited a bi-layered structure, involving inner ductal cells and clear outer myoepithelial cells. Immunostaining indicated that the inner cells were positive for epithelial membrane antigen, whereas the outer cells were positive for p40. On the genetic level, the carcinoma harbored no HRAS gene mutations, whereas fluorescence in situ hybridization (FISH) of the Pleomorphic Adenoma Gene1 showed splitting signals in the carcinomatous component. We diagnosed this case as EMCa ex-PA. It is necessary to differentiate EMCa ex-PA from myoepithelial carcinoma and clear cell carcinoma, and FISH is useful for such purposes.

The Expression of Perilipin Family Proteins can be used as Diagnostic Markers of Liposarcoma and to Differentiate Subtypes

Objective: Liposarcoma is a mesenchymal malignant tumor characterized by adipocyte differentiation which is divided into four subtypes with different prognosis. Accurate histopathological diagnosis is essential for precise treatment. Perilipins, including PLIN1, PLIN2, PLIN3, PLIN4, PLIN5, is a family of lipid droplet-associated proteins that participate in lipid metabolism regulation. The role that perilipins play in sarcomas is not clear. This study aims to assess perilipins expression in subtypes of liposarcoma and various non-lipomatous sarcomas.

Methods: A large set of 245 soft tissue sarcoma paraffin-embedded samples including 66 liposarcomas and 179 non-lipomatous sarcomas were collected for tissue microarray and immunohistochemistry to assess perilipins expression.

Results: PLIN1 expression was shown in most liposarcomas (41/66) and was absent in non-lipomatous sarcomas (0/179). PLIN4 expression was shown in some liposarcomas (21/66) and was almost negative in non-lipomatous sarcomas (2/179). PLIN1 and PLIN4 expressions in liposarcoma were higher (both P<0.001) than those in non-lipomatous sarcoma. Both PLIN1 and PLIN4 also had a significant difference in liposarcoma subtypes (both P<0.001). PLIN2, PLIN3 and PLIN5 were widely expressed in liposarcomas, rhabdomyosarcomas, leiomyosarcomas, dermatofibrosarcoma protuberans, undifferentiated sarcomas, fibrosarcomas, Ewing's sarcomas and epithelioid sarcomas. PLIN2, PLIN3 and PLIN5 expressions were significantly different among non-lipomatous sarcoma (all P<0.01).

Except for PLIN3, the expression of the other four perilipin members in liposarcoma was pairwise related.

Conclusions: PLIN1 and PLIN4 can be used as diagnostic markers of liposarcoma and to differentiate liposarcoma subtypes. The combined application of whole perilipin family immunohistochemistry may help to distinguish differently differentiated sarcomas.

Diagnostic Significance of HRAS Mutations in Epithelial-Myoepithelial Carcinomas Exhibiting a Broad Histopathologic Spectrum

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor that is histologically characterized by biphasic tubular structures composed of inner ductal and outer clear myoepithelial cells. Because of its histologic variety, it is sometimes challenging to make an accurate diagnosis, and useful ancillary tests are essential for this purpose. We investigated 87 cases of EMC arising in the major and minor salivary glands and seromucinous glands in the nasal cavity or bronchus to describe the histologic features and mutation status of selected key oncogenes. Classic EMC accounted for 40.2% of all cases. Other cases showed various growth patterns and cytologic features in addition to the typical histology; cribriform patterns, a basaloid appearance, and sebaceous differentiation were relatively common (17.2% to 18.4%), whereas oncocytic/apocrine, papillary-cystic, double-clear, squamous, psammomatous, Verocay-like, and high-grade transformation were rare. HRAS mutations were found in 82.7% of EMCs and were concentrated in codon 61. There was no significant correlation between the HRAS mutation status and the histology. No EMC ex pleomorphic adenoma cases had HRAS mutations. PIK3CA and/or AKT1 mutations were the second most frequent mutations (20.7%, 6.5%, respectively) and almost always cooccurred with HRAS mutations. It is noteworthy that the HRAS mutation was not identified in any salivary gland tumor entities manifesting EMC-like features, including adenoid cystic carcinoma, pleomorphic adenoma, basal cell adenoma/adenocarcinoma, and myoepithelial carcinoma. We conclude that HRAS mutations are a frequent tumorigenic gene alteration in EMC, despite its histologic diversity. This study provides further insight into strategies for diagnosing EMC and discriminating it from its mimics.

Caracterização anatomopatológica e imuno-histoquímica dos tumores das glândulas cutâneas em cães

RESUMO O presente estudo objetivou caracterizar os aspectos anatomopatológicos e imuno-histoquímicos dos tumores das glândulas cutâneas em cães. A caracterização morfológica seguiu a classificação atualizada da Organização Mundial de Saúde. Para a caracterização imuno-histoquímica, utilizaram-se anticorpos monoclonais primários anti-citoqueratina 14 (CK14), vimentina, p63, calponina, EGFR e Ki-67. Dos animais examinados, 66,67% (18/27) eram machos e 33,33% (9/27) fêmeas, 21 tinham raça definida e seis eram sem raça definida (SRD), com idade variando entre sete e 15 anos. Dos tumores caracterizados, 40,74% eram hepatoides (11/27), 29,63% sebáceos (8/27), 25,92% apócrinos (7/27) e 3,70% meibômio (1/27). Os tumores malignos representaram 55,56%, e os benignos 44,44%. Com esses resultados, foi possível demonstrar que os tumores das glândulas cutâneas em cães são frequentes, sem predileção por raça, sexo e com idade superior ou igual a sete anos. Os anticorpos CK 14, p63, vimentina e EGFR foram imunoexpressos nas células basais, células de diferenciação sebácea dos tumores hepatoides e de meibômio e células mioepiteliais. Entretanto, a vimentina e o EGFR não demonstraram imunomarcação para os tumores sebáceos. A calponina foi um bom marcador para as células mioepiteliais. O índice de Ki-67 foi mais acentuado nos tumores malignos em relação aos benignos. No entanto, estudos futuros utilizando maior número de casos se fazem necessários.

Roles of Perilipins in Diseases and Cancers

Perilipins, an ancient family of lipid droplet-associated proteins, are embedded in a phospho-lipid monolayer of intracellular lipid droplets. The core of lipid droplets is composed of neutral fat, which mainly includes triglyceride and cholesterol ester. Perilipins are closely related to the function of lipid droplets, and they mediate lipid metabolism and storage. Therefore, perilipins play an important role in the development of obesity, diabetes, cancer, hepatic diseases, atherosclerosis, and carcinoma, which are caused by abnormal lipid metabolism. Accumulation of lipid droplets is a common phenomenon in tumor cells. Available data on the pathophysiology of perilipins and the relationship of perilipins with endocrine metabolic diseases and cancers are summarized in this mini-review. The research progress on this family offers novel insights into the therapeutic strategies for these diseases.

Parotid gland, an exceptional localization of sebaceous carcinoma: case report

BACKGROUND

Sebaceous carcinoma (SC) is a rare malignancy, occurring predominantly in eyelids. Till date, only 25 cases of sebaceous carcinoma (SC) of the parotid gland have been reported in world literature.

CASE PRESENTATION

A 33 year-old male presented with left sided laterocervical mass. Clinical examination showed enlargement of the left parotid gland, with cervical lymphadenopathy. No skin lesions were found. A resection of the gland was performed. Pathological findings were consistent with primary sebaceous carcinoma of the parotid gland.

CONCLUSION

Sebaceous carcinoma of the parotid gland is extremely uncommon. Clinical and radiological features are not specific. The aim of this report, is to describe histopathological, and immunohistochemical findings of this rare entity, and discuss differential diagnosis.

Epithelial-Myoepithelial Carcinoma of the Salivary Glands

Objective

Epithelial-myoepithelial carcinoma (EMC) is a rare neoplasm of the salivary glands. In this study, we aim to examine the demographic, clinicopathologic, and survival features of EMC using a population-based approach.

Study Design and Setting

Retrospective cohort study.

Subjects and Methods

The Surveillance, Epidemiology, and End Result (SEER) database (1973-2010) was queried for EMC of the major salivary glands. Data were analyzed with respect to various demographic and clinicopathologic factors. Survival was analyzed using the Kaplan-Meier and Cox proportional hazards models.

Results

In total, 246 cases were available for frequency analysis and 207 for survival analysis. Mean ± SD age at diagnosis was 63.8 ± 15.4 years. EMC affected females more frequently (57.3%). Distant metastases were present at diagnosis in only 4.5% of cases. Overall disease-specific survival (DSS) at 60, 120, and 180 months was 91.3%, 90.2%, and 80.7%, respectively. Patients with low-grade histology had significantly better survival at 180 months relative to those with high-grade tumors (90.6% vs 0.0%, P = .0246). When stratified by tumor size, patients with lesions >4 cm had the worst survival at 180 months (58.8%, P = .0003). All but 9 of the 207 cases available for survival analysis underwent surgery. A total of 85 patients (41.1%) received radiotherapy in addition to surgery. No survival benefit was noted for patients who received radiotherapy compared with those who did not ( P = .4832).

Conclusion

This report represents the largest series of EMC to date. Despite being regarded as a low-grade, indolent tumor, a significant fraction of our cohort underwent radiotherapy in addition to surgery, with no apparent added survival benefit.

High-grade epithelial-myoepithelial carcinoma of the parotid gland with mucous cell differentiation

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor with a low-grade malignancy, and EMC with high-grade histopathological features is exceedingly rare. Furthermore, EMC with intracellular mucin is also extremely rare. We report an uncommon case of a high-grade EMC of the parotid gland with mucous cell differentiation in a 66-year old Japanese woman who noticed a right palpable parotid mass increasing in size within a one-year period. The cytological specimen showed a focally biphasic structure and included isolated or discohesive piled-up clusters with hyaline globules surrounded by neoplastic cells with nuclear atypia. The gross examination revealed a relatively well-demarcated, multinodular gray-whitish and solid mass. Histologically, the tumor consisted of variably sized solid nests or trabeculae with central necrosis and increased mitotic activity, and invaded into adjacent skeletal muscles. Immunohistochemically, the biphasic ductal and myoepithelial differentiation of this tumor confirmed the diagnosis of high-grade EMC. Furthermore, numerous small nests with d-PAS and alcian blue-positive mucous cells predominated in about 5% of the whole tumor, and these mucous cells were encompassed by neoplastic myoepithelial cells. We should recognize this variant of EMC because we can't rule out the possibility of EMC even in the presence of mucous cells.

Recent advances in the diagnostic pathology of salivary carcinomas

This review concentrates on the most important developments since the WHO classification of 2005. In particular, the identification of specific translocations is revolutionising the way salivary tumours are considered and will have a major impact on future diagnostic practice. This is true so far in four malignancies: mammary analogue secretory, mucoepidermoid, adenoid cystic and hyalinising clear cell carcinomas. In each, the gene rearrangement is found in 80 % or more of cases. Two 2014 publications have added further possible candidates with molecular abnormalities to the list (cribriform adenocarcinoma of the tongue and minor salivary glands and epithelial-myoepithelial carcinoma), but these findings have yet to be confirmed by other investigators. The advances in molecular pathology have also allowed re-evaluation of the morphology; for example, it is now realised that the histological spectrum of hyalinising clear cell carcinoma includes intracellular mucin in over half of cases, as well as tumours with only scanty clear cells. In a separate development, it is now proposed that salivary duct carcinoma can be subdivided along molecular lines, in ways analogous to breast cancer, suggesting new therapeutic prospects in an otherwise highly aggressive malignancy.

Sebaceous-like clear cell changes in primary lung cancer

We examined two cases of primary lung cancer with sebaceous-like clear cells (SLCCs), defined as clear carcinoma cells with microvacuolated cytoplasm and centrally located nuclei, which were selected from among 281 surgical/autopsy cases of lung cancer (2/281, 0.7%). Both cases were higher stage (stage IIA and IIIA), and SLCCs were intermingled with adenocarcinoma cells of usual type. They showed minute mucin staining, no evidence of glycogen, diffuse positivity for epithelial membrane antigen and carcinoembryonic antigen, focal positivity for thyroid transcription factor-1, and negativity for Napsin A and gross cystic disease fluid protein-15. Oil red O stain and ultrastructural examination in both cases failed to reveal lipid in SLCCs. SLCCs could represent non-specific changes of lung adenocarcinoma with a relatively advanced stage, and should be discriminated from true sebaceous differentiation.

Mammary analogue secretory carcinoma of salivary glands is a lipid-rich tumour, and adipophilin can be valuable in its identification

AIMS

Mammary analogue secretory carcinoma (MASC) of salivary glands shows morphological similarities to milk-secreting mammary epithelial cells. The aim of this study was to analyse the immunohistochemical expression of adipophilin (a component of milk lipid globule membranes) and of proteins related to secretory mechanisms (STAT5a and mammaglobin) in MASC and other salivary tumours.

METHODS AND RESULTS

Ten cases of MASC (all with ETV6 translocation) and 83 other salivary carcinomas were studied. In all MASC cases, adipophilin stained numerous large lipid droplets. These droplets were minute in other salivary carcinomas, except for sebaceous carcinoma. Overexpression of STAT5a was detected in all MASC cases, but only occasionally in other carcinomas. Mammaglobin expression occurred frequently in MASC (70% of cases), whereas, in other carcinomas, it was uncommon and limited. Only MASC showed cytoplasmic reactivity for p63, particularly in papillary-cystic areas. Positivity for S100, vimentin and high molecular weight keratin was observed in 100% of MASC cases.

CONCLUSIONS

MASC is a lipid-rich tumour containing large lipid droplets covered by adipophilin. This finding can be included among its defining immunohistochemical features, and possibly represents lactation-like secretory differentiation. Strong expression of STAT5a and cytoplasmic p63 in MASC reinforces this hypothesis.

Oncocytic and apocrine epithelial myoepithelial carcinoma: novel variants of a challenging tumor

Epithelial myoepithelial carcinoma (EMCa) is a rare but well characterized biphasic salivary gland malignancy with several variant morphologies. Oncocytic and apocrine EMCa are uncommon variants that constitute up to 8 % of all EMCa. Both variants invoke an eosinophilic or oncocytic differential diagnosis and challenge the traditional requirement of clear myoepithelial cells for EMCa. Oncocytic EMCa occurs in patients a decade older than conventional EMCa. This variant is often papillary with calcification and associated with sebaceous components and occurs in older individuals. Apocrine EMCa is named for its apocrine ductal component, which may be mistaken for salivary duct carcinoma. In this variant, the epithelial component often shows overgrowth in a cribriform or even solid pattern and is immunophenotypically defined by androgen receptor and gross cystic disease fluid protein 15 positivity. The most important aspect of differentiating both oncocytic and apocrine EMCa from other salivary oncocytic tumors is recognition of the biphasic nature of these variants and confirmation that the abluminal outer layer consists of plump, 'activated' myoepithelial cells, regardless of tinctorial characteristics. Both oncocytic and apocrine EMCa behave very indolently in the limited literature to date.

Takahashi R, Nagai T, Yoshida M, Suzuki F, Obikane H, Yamashina M, Matsubayashi J. Immunohistochemical analysis of salivary gland tumors: application for surgical pathology practice

Salivary gland tumors are relatively uncommon and there exists a considerable diagnostic difficulty owing to their diverse histological features in individual lesions and the presence of a number of types and variants, in addition to overlapping histological patterns similar to those observed in different tumor entities. The classification is complex, but is closely relevant to the prognostic and therapeutic aspects. Although hematoxylin-eosin staining is still the gold standard method used for the diagnosis, immunohistochemistry (IHC) can enhance the accuracy and be a helpful tool when in cases to investigate the subjects that cannot be assessed by histological examination, such as the cell nature and differentiation status, cell proliferation, and tumor protein expression. This review depicts on the practical diagnostic utility of IHC in salivary gland tumor pathology under the following issues: assessment of cell differentiation, focusing on neoplastic myoepithelial cells; discrimination of histologically mimic tumor groups; diagnosis of specific tumor types, e.g., pleomorphic adenoma, adenoid cystic carcinoma, and salivary duct carcinoma; and evaluation of malignancy and prognostic factors. IHC plays a limited, even though important, role in the diagnosis of salivary gland tumors, but is often useful to support the histological assessment. However, unfortunately few tumor type-specific markers are still currently available. For these reasons, IHC should be considered a method that can be used to assist the final diagnosis, and its results themselves do not directly indicate a definitive diagnosis.

Epithelial-myoepithelial carcinoma with high grade transformation

Epithelial-myoepithelial carcinoma (EMC) is a rare low-grade salivary gland malignancy of presumed intercalated duct origin comprising 1% of all salivary gland tumours. High grade transformation (HGT) in EMC is a recently recognised entity with only a few cases reported in the literature. The authors report an additional case of EMC with HGT involving the submandibular gland. The patient was a 60-year-old woman who requested examination of the rapid growth of a mass in the left submandibular area, which she had first noticed 20 years previously. Histologically, the tumour had two distinct carcinomatous components. One component had features of a low grade EMC. The second component consisted of polygonal cells, arranged in a solid and nested pattern, with marked nuclear pleomorphism, brisk mitotic activity, and frequent necrosis. The Ki-67 labelling index of the EMC component was 9%, and that of the high grade component was 40%. The patient developed multiple pulmonary metastases 15 months after surgery. The aggressive behaviour of EMC with HGT suggests that it is important to recognise this variant of EMC to avoid misdiagnosis and inappropriate treatment.

My journey into the world of salivary gland sebaceous neoplasms

As part of this symposium honoring Leon Barnes, the authors were asked to present the case from which they learned the most. I chose a cystic sebaceous lymphadenoma (SL) as my case presentation. This paper presents this unusual case, as well as several additional sebaceous tumors that came across my desk the first few years I was in practice. These interesting cases led me to thoroughly review the literature on sebaceous tumors of the salivary glands, resulting in several publications, the largest series of sebaceous tumors published at this time as well as a careful review of all cases in the literature. The author will also review the current and previous literature on the five types of salivary gland sebaceous tumors: sebaceous adenoma, SL (and non-sebaceous lymphadenoma), sebaceous carcinoma, sebaceous lymphadenocarcinoma, and sebaceous differentiation in other types of salivary gland lesions.

Rare Malignant and Benign Salivary Gland Epithelial Tumors

Although at least 24 distinct histologic salivary gland carcinomas exist, many of them are rare, comprising only 1% to 2% of all salivary gland tumors. These include epithelial-myoepithelial carcinoma, (hyalinizing) clear cell carcinoma, basal cell adenocarcinoma, cystadenocarcinoma, low-grade salivary duct carcinoma (low-grade cribriform cystadenocarcinoma), oncocytic carcinoma, and adenocarcinoma not otherwise specified. Few tumors (clear cell carcinoma and basal cell adenocarcinoma) have unique molecular correlates. Benign tumors, although histologically less diverse, are far more common, with pleomorphic adenoma and Warthin tumor the most common salivary gland tumors. Many benign tumors have malignant counterparts for which histologic distinction can pose diagnostic challenge.

Adipophilin expression in sebaceous tumors and other cutaneous lesions with clear cell histology: an immunohistochemical study of 117 cases

Adipophilin is a monoclonal antibody against a protein on the surface of intracellular lipid droplets, and it was recently shown to be expressed in sebocytes and sebaceous lesions. This study examines adipophilin expression in various sebaceous lesions and other cutaneous tumors with a clear cell histology that may mimic sebaceous differentiation. A total of 117 cutaneous clear cell lesions including 16 sebaceous adenomas, 25 sebaceous carcinomas, 8 basal cell carcinomas, 12 squamous cell carcinomas, 6 xanthomas, 10 xanthelasmas, 10 xanthogranulomas, 4 balloon cell nevi, 5 trichilemmomas, 8 clear cell hidradenomas, and 13 metastatic renal cell carcinomas were examined using immunohistochemistry for the expression of adipophilin. Of these 117 lesions, 42 (36%) were from the periocular region. Adipophilin was expressed in 16 of 16 (100%) sebaceous adenomas, 23 of 25 (92%) sebaceous carcinomas, 10 of 10 (100%) xanthelasmas, 9 of 10 (90%) xanthogranulomas, 6 of 6 (100%) xanthomas, and 9 of 13 (62.5%) metastatic renal cell carcinomas. The characteristic staining pattern differed between sebaceous and non-sebaceous tumors with the former showing a membranous vesicular pattern and the latter being more granular. Adipophilin expression was not seen in any of the other lesions with clear cell histology, basal cell carcinomas, or squamous cell carcinomas, including cases that had focal clear cell differentiation. Adipophilin can be valuable in an immunohistochemical panel when evaluating cutaneous lesions with clear cell histology as it identifies intracytoplasmic lipid vesicles in sebaceous and xanthomatous lesions. In periocular lesions, it is effective in helping to exclude basal cell carcinoma and squamous cell carcinoma when sebaceous carcinoma is under consideration. Adipophilin expression is not as useful for the differential diagnosis that includes metastatic renal cell carcinoma, a rare but important, diagnostic differential. The pattern of adipophilin reactivity is important to observe as membranous vesicular staining is suggestive of intracellular lipids whereas granular cytoplasmic reactivity is not.

Intratarsal keratinous cysts of the Meibomian gland: distinctive clinicopathologic and immunohistochemical features in 6 cases

PURPOSE

To describe 6 patients representing a new entity of Meibomian gland keratinous cysts.

DESIGN

Retrospective, interventional, clinicopathologic study.

METHODS

Review of clinical histories and findings, histopathologic evaluations, and immunohistochemical studies of the cysts' linings with monoclonal antibodies directed against cytokeratins and cell surface epithelial markers.

RESULTS

Six patients with an average age of 62.5 years had noninflamed, upper eyelid nodules fixed to the tarsus. Eyelid eversion revealed a white-yellow nodular bulge in 3 cases, a bluish coloration in 2 cases, and a translucent appearance in 1 case. The cysts were lined by undulating squamous epithelium possessing an inner eosinophilic cuticle that produced a peculiar refractile, strand-like intracavitary keratin. Immunostaining for cytokeratin 17 and carcinoembryonic antigen showed strongly positive results in the Meibomian gland cysts and, by comparison, negative results in cutaneous epidermal cysts. Multiple recurrences occurred after incomplete excisions.

CONCLUSIONS

After chalazia and sebaceous cell tumors, Meibomian gland keratinous cysts seem to be the third most common primary intratarsal lesion. Anterior fixation to the tarsus and posterior protrusion beneath the palpebral conjunctiva without inflammation suggest the diagnosis. Histopathologic and immunohistochemical evaluations can distinguish unequivocally the current entity from common epidermal cysts. The optimal treatment consists of an en bloc excision of the cyst with a tarsectomy, or else wide excision with intratarsal cautery of any remnants of the cellular lining.

PAT proteins, an ancient family of lipid droplet proteins that regulate cellular lipid stores

The PAT family of lipid droplet proteins includes 5 members in mammals: perilipin, adipose differentiation-related protein (ADRP), tail-interacting protein of 47 kDa (TIP47), S3-12, and OXPAT. Members of this family are also present in evolutionarily distant organisms, including insects, slime molds and fungi. All PAT proteins share sequence similarity and the ability to bind intracellular lipid droplets, either constitutively or in response to metabolic stimuli, such as increased lipid flux into or out of lipid droplets. Positioned at the lipid droplet surface, PAT proteins manage access of other proteins (lipases) to the lipid esters within the lipid droplet core and can interact with cellular machinery important for lipid droplet biogenesis. Genetic variations in the gene for the best-characterized of the mammalian PAT proteins, perilipin, have been associated with metabolic phenotypes, including type 2 diabetes mellitus and obesity. In this review, we discuss how the PAT proteins regulate cellular lipid metabolism both in mammals and in model organisms.

Control elements in the neighboring ATPase gene influence spatiotemporal expression of the human agouti-related protein

The agouti-related protein (AgRP) is an orexigenic peptide that plays a significant role in the regulation of energy balance. It is expressed in the hypothalamus, the adrenal glands, and the testis, but sequences determining its spatial and temporal expression have not been identified. Using an elaborate in vitro screening approach, we show here that two adjacent enhancers inside the first intron of the neighboring (1.4 kb downstream) ATPase gene (ATP6V0D1) modulate the human AgRP promoter with profound spatiotemporal variation despite their diminutive sizes (221 and 231 nt). In transgenic mice, the proximal enhancer displayed specificity for the testis, tail, and ears, and the distal one for the testis, front feet, bone, heart, muscle, brain, spinal cord, and tongue, while dietary fat and overnight fasting had differential effects on enhancer activities. AgRP in the testis was localized to pachytene spermatocytes and in the tongue to epithelial cells. Comparative sequence analysis showed that the AgRP-ATP6V0D1 intergenic region is two times longer in humans than in mice and that the two enhancers are conserved in the rhesus monkey genome but not in the mouse genome. These data show that spatiotemporal expression of the human AgRP gene is influenced by diversified primate-specific intronic sequences in its neighboring ATP6V0D1 gene.