Pulmonary tumourlets refer to a type of neuroendocrine cell proliferation in the lung. They are at the benign end of the spectrum of neuroendocrine cell proliferation when diffuse idiopathic pulmonary neuroendocrine cell hyperplasia DIPNECH breach basement membrane but remain less than 5 mm in diameter.
There is a recognised female predilection. Tumourlets are generally encountered in patients around 60 to 70 years of age 2.
Most patients tend to be asymptomatic at diagnosis.
They are thought to represent tiny peripheral pulmonary carcinoids that differ mainly in size from the larger lesions identified as carcinoid tumours with which they share histological, ultrastructural, and immunohistochemical features . Due to this, they are also called pulmonary carcinoid tumourlets by some authors 4. Tumourlets are usually defined as lesions <5 mm in diameter. They are often multiple.
Tumourlets also lack mitotic activity and do not show necrosis 5.
CT - HRCT chest
Pulmonary tumourlets may be seen as small pulmonary nodules and mosaic attenuation secondary to air trapping on CT.
- 1. Koo CW, Baliff JP, Torigian DA et-al. Spectrum of pulmonary neuroendocrine cell proliferation: diffuse idiopathic pulmonary neuroendocrine cell hyperplasia, tumorlet, and carcinoids. AJR Am J Roentgenol. 2010;195 (3): 661-8. AJR Am J Roentgenol (full text) - doi:10.2214/AJR.09.3811 - Pubmed citation
- 2. Ginsberg MS, Akin O, Berger DM et-al. Pulmonary tumorlets: CT findings. AJR Am J Roentgenol. 2004;183 (2): 293-6. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Armbruster C, Bernhardt K, Setinek U. Pulmonary tumorlet: a case report of a diagnostic pitfall in cytology. Acta Cytol. 2008;52 (2): 223-7. Pubmed citation
- 4. Kuo CL, Ho WL, Lin CC et-al. Pulmonary carcinoid tumor-tumorlet type: a case report. Zhonghua Yi Xue Za Zhi (Taipei). 1995;55 (4): 339-42. Pubmed citation
- 5. He P, Gu X, Wu Q et-al. Pulmonary carcinoid tumorlet without underlying lung disease: analysis of its relationship to fibrosis. J Thorac Dis.;4 (6): 655-8. doi:10.3978/j.issn.2072-1439.2012.06.11 - Free text at pubmed - Pubmed citation
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