Pulmonary carcinoid tumorlets (PCTs) have been detected incidentally in the explanted lungs of a number of patients following lung transplantation, according to a single-center, retrospective cohort study published in Transplantation Proceedings.

Between January 1999 and October 2020, the explanted lungs of all patients who had undergone lung transplantation at Washington University School of Medicine, Division of Cardiothoracic Surgery in St Louis, Missouri, were examined. The analysis comprised 1367 patients.

Overall, an incidental PCT was found in 1.1% (15 of 1367) of the patients who were evaluated. PCT was defined as a “nodular proliferation <5 mm with invasion beyond the membrane.”

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Underlying pulmonary indications for lung transplantation included the following:

  • Chronic obstructive pulmonary disease (COPD): 60% (9 of 15 patients)
  • Interstitial lung disease: 13% (2 of 15 patients)
  • Pulmonary vascular disease: 13% (2 of 15 patients)
  • Alpha-1 antitrypsin deficiency (AATD): 7.0% (1 of 15 patients)
  • Bronchiectasis: 7.0% (1 of 15 patients).

The median age of the patients in whom PCTs were detected was 59 years (range, 57-62 years). Of the 15 patients , 9 were women and 6 were men. Among the cohort, 78.6% (11 of 15) were former smokers.

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The median follow-up was 61.0 months (range, 19.0-167.0 months). The 5-year overall survival rate in the group was 66.7%. None of the patients reported any PCT recurrences, progression to a carcinoid tumor, or lung cancer following lung transplantation.

Based on imaging performed prior to transplantation, none of the patients were diagnosed with PCT preoperatively and no nodules were detected. Thirteen of the 15 participants (86.7%) underwent bilateral lung transplantation, with a PCT revealed in the right lung in 10 of these patients. Overall, 13 of the 15 individuals had 1 lesion, 1 patient had 2 lesions, and 1 patient had multiple lesions.

The PCTs were discovered mainly in middle-aged women. COPD was the predominant end-stage pulmonary disease in which PCT occurred.

PCT is a rare disease typically discovered incidentally on lung biopsy or at histopathologic examination. Although PCT can present as solitary or multiple lesions, the majority of the patients in the current study had solitary lesions. Although “PCT is generally uncommon,” the researchers noted, “when it occurs, it occurs more frequently on the right side and in female patients with end-stage pulmonary disease.” They concluded, “[COPD] may be a predisposing factor for developing PCT.”


Terada Y, Hachem RR, Pasque MK, et al. Pulmonary carcinoid tumorlet in the explanted lungs for lung transplantation: a case series of 15 patients. Transplant Proc. Published online February 12, 2023. doi:10.1016/j.transproceed.2023.01.004