Clinicopathological and immunohistochemical analysis of spindle-cell carcinoid tumour of the lung

Clinical and Pathologic Characteristics of Pulmonary Carcinoid Tumors in Central and Peripheral Locations

Pulmonary carcinoid tumors occur in both central and peripheral locations, and some differences in clinico-pathological features have long been observed. We investigated a large number of resected carcinoid tumors with the aim to further define the characteristics of tumors from both locations. One hundred sixty-six resected carcinoid tumors of the lung were analyzed for a variety of clinical and pathologic features, including histology subtype, mitotic rate, Ki67 index, necrosis, invasive pattern, architectural pattern, cell morphology, sustentacular cells, neuroendocrine hyperplasia, and orthopedia homeobox protein (OTP) and TTF-1 immunohistochemical expressions. Unsupervised hierarchical cluster analysis suggested three clusters as the best solution using TTF-1 and OTP expression: TTF-1-positive and OTP-positive tumors as cluster 1, TTF-1-positive but OTP-negative as cluster 2, and TTF-1-negative and OTP-negative as cluster 3. Cluster 1 was characterized by peripheral location, presence of spindle cell component, presence of sustentacular cells, female predominance, and strong association with neuroendocrine hyperplasia. Cluster 2 was characterized by central location, polygonal cell morphology, acinar growth pattern in a subset of tumors, and only rare association with neuroendocrine hyperplasia. Cluster 3 consisted of more aggressive tumors with more heterogeneous pathologic features. Tumors showed polygonal cell morphology and acinar growth pattern. Occurrence of neuroendocrine hyperplasia was exceptional. Our study confirmed distinct characteristics of central and peripheral type carcinoid. An important difference was a strong association of the peripheral tumor with neuroendocrine hyperplasia while such an association in central tumors was negligible. The tumor location might be relevant for pathobiology of lung carcinoid tumors.

Coexistence of gastric multiple neuroendocrine tumors with unusual morphological features and gastric signet-ring cell carcinoma

The coexistence of signet-ring cell carcinoma and neuroendocrine tumors is very rare. We report a 57-year-old man who presented with a history of weight loss and nausea. Gastric mucosal biopsies obtained during gastrointestinal endoscopy revealed a gastric signet-ring cell carcinoma. The patient underwent a total gastrectomy with a standard D2 lymph node dissection. Ten individual tumors were detected in the resected specimen. Based on the histopathological and immunohistochemical findings, the final diagnosis was co-existing signet-ring cell carcinoma and neuroendocrine tumor. Spindle-shaped cells and extracytoplasmic mucin were noted in some tumor cells forming the neuroendocrine component. This case is a rare synchronous tumor because of its unusual neuroendocrine component.

The impact of immunohistochemistry on the classification of lung tumors

INTRODUCTION

To highlight the role of immunohistochemistry to lung cancer classification on the basis of existing guidelines and future perspectives.

AREAS COVERED

Four orienting key-issues were structured according to an extensive review on the English literature: a) cancer subtyping; b) best biomarkers and rules to follow; c) negative and positive profiling; d) suggestions towards an evidence-based proposal for lung cancer subtyping. A sparing material approach based on a limited number of specific markers is highly desirable. It includes p40 for squamous cell carcinoma ('no p40, no squamous'), TTF1 for adenocarcinoma, synaptophysin for neuroendocrine tumors and vimentin for sarcomatoid carcinoma. A close relationship between genotype and phenotype also supports a diagnostic role for negative profiles. Expert commentary: Highly specific and sensitive IHC markers according to positive and negative diagnostic algorithms seem appropriate for individual patients' lung cancer subtyping.

A Comparative Study of Intraoperative Cytology and Frozen Sections of Sclerosing Pneumocytoma

Sclerosing pneumocytoma (SP) is a rare benign neoplasm of the lung. Conservative surgical excision is curative with an excellent prognosis. Preoperative diagnosis of SP can be difficult. Thus, intraoperative frozen sections play a crucial role in guiding surgical management. However, the interpretation of frozen section can be challenging due to freezing artifact. Intraoperative cytology provides a complementary and better morphological detail. In this study, we review and compare the intraoperative cytology and frozen section of 14 cases of SP. SP is characterized by containing 2 cell types: round stromal cells and cuboidal surface cells. The round stromal cells were small with uniform nuclei and inconspicuous nucleoli. The cuboidal surface cells were more differentiated into type II pneumocytes and showed slightly larger in size with intranuclear inclusions. The immunocytochemical double-labeling staining could display 2 distinct population of vimentin-positive round stromal cells and cytokeratin 7-positive cuboidal surface cells. Recognition of the cytological features of SP circumvents the frozen section artifact and is a useful adjunct to the frozen section in leading to the correct diagnosis of SP.

Abdominal monophasic synovial sarcoma is a morphological and immunohistochemical mimic of gastrointestinal stromal tumour

AIMS

Synovial sarcomas may arise within retroperitoneal or pelvic tissues or, more rarely, within the luminal gastrointestinal tract. This case series aims to demonstrate how such primary abdominal synovial sarcomas may particularly mimic gastrointestinal stromal tumour (GIST) on both morphological and immunohistochemical grounds.

METHODS AND RESULTS

Four cases of primary abdominal synovial sarcoma were reviewed morphologically and with immunohistochemistry, fluorescence in-situ hybridization with an SS18 break-apart probe, and KIT/PDGFRA mutation analysis. The four patients comprised two males and two females, with a median age of 42 years (range: 17-59 years). Two synovial sarcomas arose within the stomach, one within the small-intestine mesentery, and the fourth within the retroperitoneum. All four tumours showed only a monophasic spindle cell component in the tissues available for review. All four tumours showed DOG1 immunopositivity, and three coexpressed CD117. Three tested cases did not show activating KIT or PDGFRA mutations, whereas all four cases showed chromosomal rearrangement of SS18.

CONCLUSIONS

A diagnosis of synovial sarcoma should be considered particularly if an abdominal spindle cell neoplasm shows a haemangiopericytomatous pattern and diffuse CD99 and CD56 immunopositivity. A confident distinction between abdominal synovial sarcoma and GIST requires KIT/PDGFRA mutation analyses and specific molecular testing for synovial sarcoma.

Evaluation of napsin A, TTF-1, p63, p40, and CK5/6 immunohistochemical stains in pulmonary neuroendocrine tumors

OBJECTIVE

A panel of immunohistochemical (IHC) stains frequently used to subclassify non-small cell lung cancers (NSCLCs) includes napsin A, TTF-1, CK5/6, p40, and p63. The expression profiles of these stains in neuroendocrine tumors have not been systematically evaluated.

METHOD

Sixty-eight resected pulmonary neuroendocrine tumors, including 52 typical carcinoids (TCs), eight atypical carcinoids (ACs), seven small cell carcinomas (SCLCs) and one large cell neuroendocrine carcinoma (LCNEC), were stained for napsin A, TTF-1, p63, p40, and CK5/6. Tumors were scored as positive (>1% tumor cells reactive) or negative, and percentage of reactive tumor cells was recorded.

RESULTS

Napsin A, p63, p40, and CK5/6 were consistently negative in neuroendocrine tumors. TTF-1 was positive in 17 of 52 TCs, 4 of 8 ACs, 5 of 7 SCLCs, and 0 of 1 LCNECs.

CONCLUSION

Pulmonary neuroendocrine tumors have a distinct but nonspecific profile on IHC panel commonly applied to subclassify NSCLCs. They are napsin A-/p40-/p63-/CK5/6-/TTF-1±. Recognizing this profile may have value in separating neuroendocrine tumors from NSCLCs.