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pulmonary tumorlet

Tuesday 1 November 2005

pulmonary tumorlets

Definition: Carcinoid tumorlets are defined as hyperplasia of neuroendocrine cells that are 5 mm or less in size and lack of mitotic activity and necrosis.

In the respiratory system, these tumorlets share the histological, ultra-structural, and immunohistochemical features with carcinoids, and the diagnostic discrimination between the two pathologies solely relies on an arbitrarily determined physical dimension.

Pulmonary carcinoid tumorlet is almost always associated with underlying lung disease such as bronchiectasis and fibrosis, but the relationship between tumorlet and fibrosis remains to be defined.

Some researchers believed that hyperplasia of pulmonary neuroendocrine cells is an adaptive response to hypoxia or a secondary process associated with pulmonary fibrosis, while other studies suggested that neuroendocrine cells are involved in the pathogenesis of chronic lung diseases.

Pulmonary carcinoid tumorlet is a rare pathology and appears to be always associated with other lesions such as bronchiectasis and fibrosis.

While the cause-effect relationship between tumorlet and the accompanying pathological changes in the surrounding mesenchymal tissue remains to be defined, it has been postulated that pulmonary fibrosis may be the primary pathology underlying the development of tumorlet.

Pulmonary tumorlets and neuroendocrine cell hyperplasia are part of a continuous spectrum of NE-cell hyperplasia, going from NE hyperplasia to carcinoid.

Carcinoid tumorlet can be an isolated lesion and pulmonary fibrosis that “often co-exists” with tumorlet may be secondary to the paracrine effects of fibrotic growth factors produced by tumorlet. (Ref)

See also

- pulmonary neuroendocrine cell hyperplasia

References

- doi : 10.3978/j.issn.2072-1439.2012.06.11
- doi : 10.3978/j.issn.2072-1439.2012.06 11