LAUSR

The tail sign was originally described as a key CT finding of pulmonary sclerosing haemangiomas – where a small linear projection is seen radiating out from the lesion. Other findings include a prominent pulmonary artery, inhomogeneous enhancement, smooth margins and cystic spaces. The 2015 World Health Organization Classification of Lung Tumors removed the term sclerosing haemangioma as the tumour is not of vascular origin. The tumour has been renamed sclerosing pneumocytoma and is included as a subtype of adenoma. It is a tumour of pneumocytic origin with a dual population of surface cells resembling type II pneumocytes and round cells. Most tumours have at least three of four primary growth patterns: solid, papillary, sclerosing, and hemorrhagic. The key feature of sclerosing pneumocytoma is the presence of two cell types: cuboidal surface cells and stromal round cells. These tumours are described as potentially being challenging to diagnose in frozen section, small biopsies, and cytology where they can easily be mistaken for adenocarcinoma or carcinoid tumours. Despite the very rare frequency of metastases, these tumours typically have a benign clinical course. Related signs