Loss of succinate dehydrogenase B immunohistochemical expression distinguishes pulmonary chondromas from hamartomas

What's new in benign lung tumours?

While lung cancer is one of the most common malignancies routinely encountered by pathologists, benign pulmonary neoplasms are quite rare. However, it is important for pathologists to be familiar with the typical diagnostic features of benign lung tumors to avoid confusing them with malignant morphological mimics. There have also been intriguing discoveries in the genetics of benign pulmonary neoplasms in the past decade. This review will cover several of the most common benign lung tumors, including the diagnostic categories of pulmonary adenomas, bronchial papillomas, and benign mesenchymal tumors, with discussion of the current classification, differential diagnosis, and current knowledge regarding genetic drivers.

Back to Biochemistry: Evaluation for and Prognostic Significance of SDH Mutations in Paragangliomas and Pheochromocytomas

There is increasing recognition of the high prevalence of hereditary predisposition syndromes in patients diagnosed with paraganglioma/pheochromocytoma. It is widely acknowledged that germline pathogenic alterations of the succinate dehydrogenase complex genes (SDHA, SDHB, SDHC, SDHD, SDHAF2) contribute to the pathogenesis of most of these tumors. Herein, we have provided an update on the biology and diagnosis of succinate dehydrogenase-deficient paraganglioma/pheochromocytoma, including the molecular biology of the succinate dehydrogenase complex, mechanisms and consequences of inactivation of this complex, the prevalence of pathogenic alterations, and patterns of inheritance.

Overview of the 2022 WHO Classification of Familial Endocrine Tumor Syndromes

This review of the familial tumor syndromes involving the endocrine organs is focused on discussing the main updates on the upcoming fifth edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. This review emphasizes updates on histopathological and molecular genetics aspects of the most important syndromes involving the endocrine organs. We describe the newly defined Familial Cancer Syndromes as MAFA-related, MEN4, and MEN5 as well as the newly reported pathological findings in DICER1 syndrome. We also describe the updates done at the new WHO on the syndromic and non-syndromic familial thyroid diseases. We emphasize the problem of diagnostic criteria, mention the new genes that are possibly involved in this group, and at the same time, touching upon the role of some immunohistochemical studies that could support the diagnosis of some of these conditions. As pathologists play an important role in identifying tumors within a familial cancer syndrome, we highlight the most important clues for raising the suspicious of a syndrome. Finally, we highlight the challenges in defining these entities as well as determining their clinical outcome in comparison with sporadic tumors. Instead of the usual subject review, we present the highlights of the updates on familial cancer syndromes by answering select questions relevant to practicing pathologists.

Clinical, Radiologic, and Pathologic Characteristics of Pulmonary Hamartomas With Uncommon Presentation

OBJECTIVES

To investigate the clinicopathologic and radiologic features of pulmonary hamartomas (PHs) with uncommon clinical presentation.

METHODS

A retrospective clinicopathologic and radiologic review was performed for patients diagnosed (1999-2019) with multiple hamartomas, lesions arising adjacent to a coexisting pulmonary malignancy, and tumors with predominantly extrapulmonary localization.

RESULTS

Of 979 patients diagnosed with PHs, 6 (0.6%) had multiple hamartomas, 4 (0.4%) had hamartomas adjacent to lung adenocarcinoma, and 2 (0.2%) had large mediastinal masses. Patients with multiple lesions had a median age of 65 years and mean tumor size of 0.9 cm; 1 patient had 3 hamartomas, and 5 patients had 2. Lesions next to adenocarcinomas had a mean size of 1.4 cm, and affected patients had a median age of 69 years. Predominantly mediastinal PHs, diagnosed in a 63-year-old woman and a 68-year-old man, measured 4.1 to 6 cm and were connected to the lung. All lesions were solid on imaging with absence of definitive fat or calcification, concerning for granuloma or malignancy. All cases had typical histology of PH, although one of the mediastinal tumors had an unusual amount of epithelial hyperplasia.

CONCLUSIONS

PHs can be clinically and radiologically challenging to diagnose. Histopathologic examination of biopsies and resection specimens is diagnostically crucial in this setting.