Hiperplasia difusa idiopática de células neuroendocrinas pulmonares con tumores carcinoides múltiples sincrónicos

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia syndrome

The term diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) may be used to describe a clinico-pathological syndrome, as well as an incidental finding on histological examination, although there are obvious differences between these two scenarios. According to the World Health Organization, the definition of DIPNECH is purely histological. However, DIPNECH encompasses symptomatic patients with airway disease, as well as asymptomatic patients with neuroendocrine cell hyperplasia associated with multiple tumourlets/carcinoid tumours. DIPNECH is also considered a pre-neoplastic lesion in the spectrum of pulmonary neuroendocrine tumours, because it is commonly found in patients with peripheral carcinoid tumours.

In this review, we summarise clinical, physiological, radiological and histological features of DIPNECH and critically discuss recently proposed diagnostic criteria. In addition, we propose that the term “DIPNECH syndrome” be used to indicate a sufficiently distinct patient subgroup characterised by respiratory symptoms, airflow obstruction, mosaic attenuation with air trapping on chest imaging and constrictive obliterative bronchiolitis, often with nodular proliferation of neuroendocrine cells with/without tumourlets/carcinoid tumours on histology. Surgical lung biopsy is the diagnostic gold standard. However, in the appropriate clinical and radiological setting, transbronchial lung biopsy may also allow a confident diagnosis of DIPNECH syndrome.

The spectrum of changes in adults with multifocal pulmonary neuroendocrine proliferations: what is the minimum set of pathologic criteria to diagnose DIPNECH?

Diffuse idiopathic neuroendocrine cell hyperplasia (DIPNECH) can be difficult to diagnose in resections for lung tumors and other conditions, as variable diagnostic criteria and definitions of "diffuse" and/or "idiopathic" have been used in the literature. We reviewed 70 consecutive lung wedge biopsies and resection specimens with multifocal neuroendocrine cell proliferations (NEP) including neuroendocrine cell hyperplasia (NECH) and/or carcinoid tumorlets to identify pathologic findings significantly associated with neuroendocrine neoplasms. The presence of pathologic changes other than NEP (eg, interstitial fibrosis, bronchiectasis, others) and the number of tumorlets were recorded to identify "idiopathic NEP." Cases were classified into 4 groups: A: NECH only, B: >1 tumorlet without NECH, C: NECH + 2 tumorlets, and D: NECH + >2 tumorlets. Proportions of neuroendocrine neoplasms and presence/absence of pathologic changes other than NEP were compared by group with χ(2) statistics. Carcinoids were seen in 8 (22.8%) of 35 and in 21 (72.4%) of 29 groups B and D cases, respectively. Of the 21 group D carcinoids, 18 (85.7%) lacked other associated pathologic changes, and the incidence of these tumors in this group was significantly higher (P < .001) than in group B. Three high-grade neuroendocrine carcinomas were seen, 1 each in groups A to C. Because group D cases had a significantly higher proportion of carcinoid tumors and a significant lack of association with conditions that could result in secondary NECH, the presence of multifocal NECH combined with 3 or more carcinoid tumorlets is proposed as minimum pathologic criteria for the diagnosis of DIPNECH.