Peter P. Luk

Salivary duct carcinoma: Clinicopathologic features, morphologic spectrum, and somatic mutations.

Accurate diagnosis of salivary duct carcinoma requires a high index of suspicion and clinicopathologic correlation. Hallmark genetic changes that may provide novel therapeutic options are being explored.

BRAF mutations in non-small cell lung cancer

BACKGROUND BRAF is a proto-oncogene encoding a serine/threonine protein kinase which promotes cell proliferation and survival. BRAF mutations are commonly seen in melanoma and papillary thyroid carcinoma. We aimed to investigate the prevalence and clinicopathological features of BRAF mutations in non-small cell lung cancer (NSCLC) cases submitted for routine mutation testing at our institution. METHODS Mutation analysis for BRAF, EGFR and KRAS was performed using Sequenom MassARRAY platform with OncoCarta panel v1.0. Pathological features were reviewed and immunohistochemistry for BRAF V600E was also performed. RESULTS Seven out of 273 cases (2.6%) had BRAF mutations (three males and four females, median age 70 years, all smokers), with six adenocarcinomas and one NSCLC, not otherwise specified (NOS). All had wild-type EGFR and KRAS. The identified BRAF mutations were V600E (4/7, 58%), K601N, L597Q and G469V. BRAF V600E immunohistochemistry was positive in two cases with V600E and negative in one case with K601N (tissue available in three cases only). No significant difference in age or gender was found (BRAF mutant vs. wild-type). CONCLUSIONS BRAF mutations occur in a small proportion of NSCLC that lack other driver mutations. The clinicopathological profile differs from that of EGFR mutant tumours. The potential benefits of BRAF-inhibitors should be investigated.

Mammary analogue secretory carcinoma: an evaluation of its clinicopathological and genetic characteristics

Summary Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland malignancy. We evaluate the clinicopathological characteristics and long-term clinical behaviour of MASCs. A total of 190 primary salivary gland malignancies at a single institution were reviewed along with relevant immunohistochemical and fluorescent in situ hybridisation (FISH) studies to identify MASCs. Nine MASCs were identified predominantly in the parotid with an equal incidence in men and women and mean age of 36 years. The tumour size ranged from 14 to 50 mm (mean 22 mm). MASCs were composed of monotonous cells with vacuolated eosinophilic cytoplasm and a small nucleus with a distinctive nucleolus. All cases showed immunoreactivity with S-100, MUC4, CK7 and mammoglobin, and lacked immunoreactivity with DOG1, p63, CK5/6 and calponin. ETV6 rearrangement was seen in all cases. No mutations were identified using the OncoCarta Panel v1.0 Kit. Follow up was available for 0.4 to 22 years (median 4 years). Intraparotid lymph node involvement and local recurrence were seen in one patient each. There were no distant metastases. MASCs have specific histopathological features and immunohistochemical profile that distinguish them from their mimics. FISH plays a confirmatory role. An indolent long-term clinical course was observed in this cohort despite involvement of intraparotid lymph node and microscopically involved/close margins.

Diagnostic and prognostic utility of Mastermind-like 2 (MAML2) gene rearrangement detection by fluorescent in situ hybridization (FISH) in mucoepidermoid carcinoma of the salivary glands.

OBJECTIVE Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy, with a proportion harboring MAML2 rearrangement. This study evaluates the diagnostic and prognostic utility of MAML2 rearrangement in MEC. STUDY DESIGN Salivary gland malignancies at a single institution (1989-2014) were reviewed to identify MECs. Histopathologic evaluation, immunohistochemistry, and fluorescent in situ hybridization (FISH) were performed. RESULTS Forty-one cases of MEC were identified, with mean age of 47 years and mean tumor size of 21 mm. Seven locoregional recurrences and five MEC-related deaths were seen over a 22-year follow-up period. Thirty-eight cases were suitable for FISH, and 31 (82%) cases were positive for MAML2 rearrangement, including the oncocytic and clear cell variants of MEC. FISH was negative in the morphologic mimics of MEC. MAML2 rearrangement was significantly associated with longer survival. CONCLUSIONS MAML2 rearrangement is common and specific for MEC, which makes it a useful diagnostic tool. MAML2 rearrangement also predicts a favorable prognosis.

Somatic mutations in salivary duct carcinoma and potential therapeutic targets

Background Salivary duct carcinomas (SDCa) are rare highly aggressive malignancies. Most patients die from distant metastatic disease within three years of diagnosis. There are limited therapeutic options for disseminated disease. Results 11 cases showed androgen receptor expression and 6 cases showed HER2 amplification. 6 Somatic mutations with additional available targeted therapies were identified: EGFR (p.G721A: Gefitinib), PDGFRA (p.H845Y: Imatinib and Crenolanib), PIK3CA (p.H1047R: Everolimus), ERBB2 (p.V842I: Lapatinib), HRAS (p.Q61R: Selumetinib) and KIT (p.T670I: Sorafenib). Furthermore, alterations in PTEN, PIK3CA and HRAS that alter response to androgen deprivation therapy and HER2 inhibition were also seen. Materials and Methods Somatic mutation analysis was performed on DNA extracted from 15 archival cases of SDCa using the targeted Illumina TruSeq Amplicon Cancer Panel. Potential targetable genetic alterations were identified using extensive literature and international somatic mutation database (COSMIC, KEGG) search. Immunohistochemistry for androgen receptor and immunohistochemistry and fluorescent in situ hybridization for HER2 were also performed. Conclusions SDCa show multiple somatic mutations, some that are amenable to pharmacologic manipulation and others that confer resistance to treatments currently under investigation. These findings emphasize the need to develop testing and treatment strategies for SDCa.BACKGROUND Salivary duct carcinomas (SDCa) are rare highly aggressive malignancies. Most patients die from distant metastatic disease within three years of diagnosis. There are limited therapeutic options for disseminated disease. RESULTS 11 cases showed androgen receptor expression and 6 cases showed HER2 amplification. 6 Somatic mutations with additional available targeted therapies were identified: EGFR (p.G721A: Gefitinib), PDGFRA (p.H845Y: Imatinib and Crenolanib), PIK3CA (p.H1047R: Everolimus), ERBB2 (p.V842I: Lapatinib), HRAS (p.Q61R: Selumetinib) and KIT (p.T670I: Sorafenib). Furthermore, alterations in PTEN, PIK3CA and HRAS that alter response to androgen deprivation therapy and HER2 inhibition were also seen. MATERIALS AND METHODS Somatic mutation analysis was performed on DNA extracted from 15 archival cases of SDCa using the targeted Illumina TruSeq Amplicon Cancer Panel. Potential targetable genetic alterations were identified using extensive literature and international somatic mutation database (COSMIC, KEGG) search. Immunohistochemistry for androgen receptor and immunohistochemistry and fluorescent in situ hybridization for HER2 were also performed. CONCLUSIONS SDCa show multiple somatic mutations, some that are amenable to pharmacologic manipulation and others that confer resistance to treatments currently under investigation. These findings emphasize the need to develop testing and treatment strategies for SDCa.

Diagnostic and prognostic utility of mastermind-like 2 (MAML2) gene rearrangement detected by fluorescent in-situ hybridisation (Fish) in mucoepidermoid carcinoma

Aims: Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. A proportion of MECs have been shown to harbour MAML2 translocation. This study evaluates the diagnostic and prognostic utility of MAML2 in MEC. Methods: Salivary gland malignancies at Royal Prince Alfred Hospital and Sydney Head and Neck Cancer Institute (1989–2014) were reviewed to identify MECs. Histopathological evaluation, immunohistochemical and fluorescent in-situ hybridisation (FISH) studies were performed. An additional nine cases of morphological mimics of MEC were also analysed for MAML2 rearrangement. Clinical follow-up was obtained. Results: 40 cases of MEC were identified. Parotid gland was the most common site (73%). The age range was 15–79 years (mean 47 years). The tumour size ranged from 4–70 mm (mean 22 mm). Thirty-seven cases were suitable for FISH and 31 (84%) cases were positive for MAML2 translocation, including oncocytic and clear cell variants of MEC. The nine morphological mimics of MEC did not show MAML2 rearrangement. MAML2 translocation did not correlate with histological grade, stage, nodal metastases, recurrence or survival, limiting its prognostic utility. Conclusion: FISH for MAML2 rearrangement has high sensitivity and specificity for MEC. Thus it is a useful diagnostic tool, particularly in cases with limited material or variant morphology.

Punch biopsy of melanoma causing tumour cell implantation: Another peril of utilising partial biopsies for melanocytic tumours

The recommended initial management for suspected melanoma is excisional biopsy. The use of partial biopsies of melanocytic tumours poses potential problems including misdiagnosis due to either unrepresentative sampling or the difficulty in evaluating important diagnostic features; an inaccurate assessment of Breslow thickness and other important prognostic features; and the induction of changes capable of mimicking melanoma (i.e., pseudomelanoma). Misdiagnosis, in turn, may lead to inappropriate management of the patient and an adverse outcome. In this report we document a previously unrecognised pitfall of partial biopsies of melanocytic tumours: implantation of tumour cells at the biopsy site potentially leading to the overestimation of tumour thickness or a misdiagnosis of the presence of microsatellites in the subsequent wide excision specimen.

Biomarkers for ALK and ROS1 in Lung Cancer: Immunohistochemistry and Fluorescent In Situ Hybridization

CONTEXT - A small proportion of non-small cell lung cancers harbor rearrangements of ALK or ROS1 genes, and these tumors are sensitive to targeted tyrosine kinase inhibitors. It is crucial for pathologists to accurately identify tumors with these genetic alterations to enable patients to access optimal treatments and avoid unnecessary side effects of less effective agents. Although a number of different techniques can be used to identify ALK- and ROS1-rearranged lung cancers, immunohistochemistry and fluorescence in situ hybridization are the mainstays. OBJECTIVE - To review the role of immunohistochemistry in assessment of ALK and ROS1 rearrangements in lung cancer, focusing on practical issues in comparison with other modalities such as fluorescence in situ hybridization. DATA SOURCES - This manuscript reviews the current literature on ALK and ROS1 detection using immunohistochemistry and fluorescence in situ hybridization as well as current recommendations. CONCLUSIONS - Although fluorescence in situ hybridization remains the gold standard for detecting ALK and ROS1 rearrangement in non-small cell lung cancer, immunohistochemistry plays an important role and can be an effective screening method for detection of these genetic alterations, or a diagnostic test in the setting of ALK.

Primary salivary gland malignancies: a review of clinicopathological evolution, molecular mechanisms and management

Salivary gland cancers are a complex group of tumours with variations in location, type and grade, all of which influence their biological behaviour. The understanding of salivary gland pathology has evolved at the molecular level in the last decade leading to identification of distinct entities, development of improved methods of diagnosis as well as identifying therapeutic targets for selected high‐grade tumours. This article focuses on these advances and their impact on the management of primary salivary gland cancers.

Metastatic adenoid cystic carcinoma of the liver confirmed with MYB rearrangement

S S135 Background: CD5 is an antigen normally expressed on T-cells but can also be expressed in a small subset of B-cells and some non-Hodgkin B-cell lymphoproliferative disorders such as small lymphocytic lymphoma, marginal zone lymphoma and mantle cell lymphoma. When using a single immunohistochemical stain for each antigen on separate slides, it can be challenging to compare and correlate whether CD5 positivity is being seen in neoplastic B-cells or normal T-cells. This problem is amplified when the CD5 expressing B-cells are present in small numbers, such as in a bone marrow trephine. Aim: In addition to the usual panel of immunohistochemical stains, we describe the application of two T-cell markers in a combined stain, CD5 (red, cytoplasmic) / CD3 (brown, cytoplasmic), to aid in the identification of CD5 co-expressing Bcells in small B-cell lymphoproliferative disorders. Method: In a suspected small B-cell lymphoproliferative disorder, the red CD5 immunohistochemical stain is applied first and is positive in all normal T-cells and CD5-expressing B-cells. The brown CD3 stain is applied second, and also stains all the normal T-cells that express both CD3 and CD5, but does not stain any of the B-cells. As the darker brown stain is applied over the red, all CD3 and CD5 expressing T-cells that have been stained twice only appear brown, whereas the CD5 expressing Bcells appear red. Conclusion: Following the application of these two T-cell markers to a single slide, it can be deduced that all brown staining cells are normal CD3 / CD5 expressing T-cells whereas the red staining cells are CD5-expressing B-cells. 55. NEOPLASIA IN GASTRIC ADENOCARCINOMA AND PROXIMAL POLYPOSIS SYNDROME (GAPPS): GASTRIC RATHER THAN INTESTINAL PHENOTYPE Priyanthi Kumarasinghe, W. Bastiaan de Boer, M. Hooi Ee