Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia with a central and peripheral carcinoid and multiple tumorlets: a case report emphasizing the role of neuropeptide hormones and human gonadotropin-alpha

Progastrin-Releasing Peptide As a Diagnostic Biomarker of Pulmonary and Non-Pulmonary Neuroendocrine Neoplasms

BACKGROUND

Progastrin-releasing peptide (ProGRP) is the precursor of the gastrin-releasing peptide, a neuropeptide secreted by cells of neural and endocrine origin. Recently, ProGRP has emerged as a circulating biomarker for small cell lung cancer (SCLC), a subtype of aggressive and poorly differentiated neuroendocrine neoplasm (NEN). Given the ability of the neuroendocrine SCLC cells to secrete this peptide, we performed an in-depth narrative review aimed at collecting, summarizing, and critically analyzing the available literature about the possible value of ProGRP as a biomarker for pulmonary NENs other than SCLC, and for NENs of non-pulmonary origin.

METHODS

We conducted an extensive search on international databases (PubMed, Web of Science, and Scopus).

RESULTS

We selected 21 pertinent published articles (12 original studies and 9 case reports). Overall, the original studies included 1,711 patients, and the case reports described the clinical course of 10 patients.

CONCLUSION

The data analyzed suggest a potential role for ProGRP as a diagnostic biomarker for typical and atypical lung carcinoids, pulmonary large cell neuroendocrine carcinoma, medullary thyroid carcinoma, non-pulmonary neuroendocrine carcinomas, prostate cancer with neuroendocrine differentiation, and the pancreatobiliary neuroendocrine carcinoma. Despite these promising results, additional studies are needed, to clarify the role of ProGRP as the diagnostic biomarker for specific NENs.

Pulmonary Function Tests as a Biomarker in Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia Patients Treated With Somatostatin Analogues

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) describes an indolent, under-recognised and poorly understood pulmonary condition with fewer than 200 reported cases across the literature. Currently, cases are diagnosed following a biopsy of the primary lesion, with treatment options centring on symptomatic benefit as opposed to targeting the underlying aetiology. Classically, DIPNECH lesions have been described as slow growing and benign, but with growing awareness of the condition, reports of metastatic disease with significant symptomatic burden have been reported. However, effectively addressing the subset of DIPNECH patients with greater metastatic potential remains an unmet clinical need. Due to the similarities between DIPNECH and carcinoid patients, several centres have considered using somatostatin analogues to not only help symptomatically but also to initiate tumour regression. However, to date, there are limited biomarkers to help evaluate the benefit of such options. In this review, we consider the use of pulmonary function tests (PFTs) to help quantify the benefit of somatostatin analogues. Although much of the evidence stems from small single-centre studies, the use of PFTs within the treatment pathway for both localised and metastatic DIPNECH represents a meaningful improvement from subjective monitoring of disease.

Ten Years of Chronic Cough in a 64-Year-Old Man With Multiple Pulmonary Nodules

A 64-year-old male former smoker with a history of prostate cancer presented to our pulmonary clinic, complaining of nonproductive cough for 10 years. Prior evaluation included treatment for upper airway cough syndrome and gastroesophageal reflux, stopping angiotensin-converting enzyme inhibitor, and initiation of inhaled β-agonists. Esophageal pH monitoring indicated silent reflux, and proton pump inhibitor therapy was started. He continued to cough and complain of dyspnea. Physical examination produced unremarkable results, with no evidence of lymphadenopathy. Pulmonary function tests showed a pseudo-restrictive pattern with air trapping, hyperreactivity, and incomplete bronchodilator responsiveness: FEV1, 2.48 L (69% of predicted); FVC, 3.57 L (75% of predicted); FEV1/FVC, 92%; total lung capacity, 7.00 L (100% of predicted); and residual volume, 3.05 L (136% of predicted). Laboratory studies, including a complete metabolic panel, prostate-specific antigen test, and complete blood count, yielded normal results.

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 neuroendocrine tumors: histologic classification, unique features and areas of overlap

Neuroendocrine neoplasms are diverse in terms of sites of origin, functional status, and degrees of aggressiveness. This review will introduce some of the common features of neuroendocrine neoplasms and will explore the differences in pathology, classification, biology, and clinical management between tumors of different anatomic sites, specifically, the lung, pancreas, and prostate. Despite sharing neuroendocrine differentiation and histologic evidence of the neuroendocrine phenotype in most organs, well-differentiated neuroendocrine tumors (WD-NETs) and poorly differentiated neuroendocrine carcinomas (PD-NECs) are two very different families of neoplasms. WD-NETs (grade 1 and 2) are relatively indolent (with a natural history that can evolve over many years or decades), closely resemble non-neoplastic neuroendocrine cells, and demonstrate production of neurosecretory proteins, such as chromogranin A. They arise in the lungs and throughout the gastrointestinal tract and pancreas, but WD-NETs of the prostate gland are uncommon. Surgical resection is the mainstay of therapy, but treatment of unresectable disease depends on the site of origin. In contrast, PD-NECs (grade 3, small cell or large cell) of all sites often demonstrate alterations in P53 and Rb, exhibit an aggressive clinical course, and are treated with platinum-based chemotherapy. Only WD-NETs arise in patients with inherited neuroendocrine neoplasia syndromes (e.g., multiple endocrine neoplasia type 1), and some common genetic alterations are site-specific (e.g., TMPRSS2-ERG gene rearrangement in PD-NECs arising in the prostate gland). Advances in our understanding of the molecular basis of NETs should lead to new diagnostic and therapeutic strategies and is an area of active investigation.

Pathologic Classification of Neuroendocrine Neoplasms

The pathologic classification of neuroendocrine neoplasms has evolved over the past decades, as new understanding of the biological behavior, histologic characteristics, and genetic features have emerged. Nonetheless, many aspects of the classification systems remain confusing or controversial. Despite these difficulties, much progress has been made in determining the features predicting behavior. Genetic findings have helped establish relationships among different types of neuroendocrine neoplasms and revealed potential therapeutic targets. This review summarizes the current approach to the diagnosis, classification, grading, and therapeutic stratification of neuroendocrine neoplasms, with a focus on those arising in the lung and thymus, pancreas, and intestines.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH)

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a pre-invasive generalized proliferation of pulmonary neuroendocrine (PNE) cells, which has been described in combination with carcinoid tumorlets, obliterative bronchiolitis, and other fibrotic lung changes. Since its first recognition as a distinct syndrome in 1992, variable clinico-pathologic features have been used to diagnose DIPNECH in small case series and case reports. We recently proposed the use of the following criteria for the pathologic diagnosis of the syndrome on lung resection specimens: the presence of multifocal neuroendocrine cell hyperplasia, as defined by the presence of 5 or more PNE cells in at least 3 separate small airways combined with 3 or more carcinoid tumorlets. At diagnosis, 53% of DIPNECH patients present with a synchronous carcinoid tumor and 24% have obliterative bronchiolitis. To our knowledge, only 1 patient has been diagnosed with a carcinoid tumor subsequent to a DIPNECH diagnosis and the syndrome is not associated with an increased incidence of high-grade neuroendocrine neoplasms. Patients have usually a stable disease and only 26% experience clinical and/or radiographic deterioration. There is no evidence that treatment with octreotide or other medications improves the prognosis of DIPNECH patients.

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.

Medullary carcinoma of the thyroid metastatic to the breast: a case report and literature review

Breast malignancies, apart from skin cancer, are the leading cause of cancer from cancer among the female population. Unlike the high prevalence of primary mammary malignancies, metastases to the breast are uncommon, and account for only 0.2-2.7% of all malignancies affecting this organ. We report the case of a 35-year-old woman who sought medical care because of a breast lump. A mammogram suggested a breast tumor, which was biopsied. The histopathological workup resulted in the diagnosis of a metastasis from a medullary thyroid cancer. The authors review the most useful clinical, radiological, histological, and immunohistochemical features concerning extramammary malignancy to the breast.