Somatostatin Analogs Improve Respiratory Symptoms in Patients With Diffuse Idiopathic Neuroendocrine Cell Hyperplasia

A Rare Case of Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia: A Case Report

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare pulmonary disease characterized by the diffuse proliferation of neuroendocrine cells in the bronchial epithelium. It is considered a preinvasive precursor to carcinoid tumors and usually presents with obstructive symptoms. We present the case of a 71-year-old female, non-smoker, with a past medical history of asthma, osteoarthritis, allergic rhinitis, and hyperlipidemia who was referred to the pulmonology clinic in view of incidental chest CT findings of multiple pulmonary nodules. Physical examination and labs were unremarkable. CT of the chest showed scattered multiple noncalcified pulmonary nodules with a 10 mm dominant nodule in the inferior right middle lobe and several subcentimeter hypodensities in the left and right lobes of the lung. A PET scan confirmed the CT findings along with no abnormal hypermetabolic activity to suggest malignancy. The patient was followed up in the pulmonology clinic at six months, 12 months, and then 18 months. At 18 months owing to a slight increase in the size of the largest lung nodule, a CT-guided biopsy done was conclusive of a carcinoid. The tumor cells were positive for synaptophysin, chromogranin, insulinoma-associated protein 1 (INSM-1), and thyroid transcription factor 1 (TTF-1). The Ki-67 (Keil) index was <1%. A video-assisted thoracic surgery with right middle lobectomy along with mediastinal lymph node dissection was then done, and the patient was found to have stage pT1aN0 typical carcinoid tumor (1.0 cm), with multiple carcinoid tumors and neuroendocrine hyperplasia, consistent with DIPNECH. She has been under clinical follow-up for over three years at present and continues to be asymptomatic with complete remission following surgery. DIPNECH primarily affects middle-aged, non-smoking females who present with cough and dyspnea, and diagnosis is often delayed due to clinical features overlapping with those of obstructive lung disease. Imaging shows lung nodules, ground-glass opacities, and/or mosaic attenuation. Due to the rarity of the conditions, there are no established clinical trials, and therefore, there is a need to establish guidelines.

Investigating pulmonary neuroendocrine cells in human respiratory diseases with airway models

Despite accounting for only ∼0.5% of the lung epithelium, pulmonary neuroendocrine cells (PNECs) appear to play an outsized role in respiratory health and disease. Increased PNEC numbers have been reported in a variety of respiratory diseases, including chronic obstructive pulmonary disease and asthma. Moreover, PNECs are the primary cell of origin for lung neuroendocrine cancers, which account for 25% of aggressive lung cancers. Recent research has highlighted the crucial roles of PNECs in lung physiology, including in chemosensing, regeneration and immune regulation. Yet, little is known about the direct impact of PNECs on respiratory diseases. In this Review, we summarise the current associations of PNECs with lung pathologies, focusing on how new experimental disease models, such as organoids derived from human pluripotent stem cells or tissue stem cells, can help us to better understand the contribution of PNECs to respiratory diseases.

Lung Carcinoids: A Comprehensive Review for Clinicians

Lung carcinoids are neuroendocrine tumors, categorized as typical or atypical carcinoids based on their histological appearance. While most of these tumors are slow-growing neoplasms, they still possess malignant potential. Many patients are diagnosed incidentally on chest X-rays or CT scans. Presenting symptoms include cough, hemoptysis, wheezing, dyspnea, and recurrent pneumonia. Endocrine symptoms, such as carcinoid syndrome or ectopic Cushing's syndrome, are rare. Surgery is the primary treatment and should be considered in all patients with localized disease, even when thoracic lymph node metastases are present. Patients with distant metastases may be treated with somatostatin analogues, chemotherapy, preferably temozolomide-based, mTOR inhibitors, or peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE. Most patients have an excellent prognosis. Poor prognostic factors include atypical histology and lymph node metastases at diagnosis. Long-term follow-up is mandatory since metastases may occur late.

Quantitative Airway Assessment of Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia (DIPNECH) on CT as a Novel Biomarker

Objectives: Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) occurs due to abnormal proliferation of pulmonary neuroendocrine cells. We hypothesized that performing a quantitative analysis of airway features on chest CT may reveal differences to matched controls, which could ultimately help provide an imaging biomarker. Methods: A retrospective quantitative analysis of chest CTs in patients with DIPNECH and age matched controls was carried out using semi-automated post-processing software. Paired segmental airway and artery diameters were measured for each bronchopulmonary segment, and the airway:artery (AA) ratio, airway wall thickness:artery ratio (AWTA ratio) and wall area percentage (WAP) calculated. Nodule number, size, shape and location was recorded. Correlation between CT measurements and pulmonary function testing was performed. Results: 16 DIPNECH and 16 control subjects were analysed (all female, mean age 61.7 +/− 11.8 years), a combined total of 425 bronchopulmonary segments. The mean AwtA ratio, AA ratio and WAP for the DIPNECH group was 0.57, 1.18 and 68.8%, respectively, compared with 0.38, 1.03 and 58.3% in controls (p < 0.001, <0.001, 0.03, respectively). DIPNECH patients had more nodules than controls (22.4 +/− 32.6 vs. 3.6 +/− 3.6, p = 0.03). AA ratio correlated with FVC (R2 = 0.47, p = 0.02). A multivariable model incorporating nodule number, AA ratio and AWTA-ratio demonstrated good performance for discriminating DIPNECH and controls (AUC 0.971; 95% CI: 0.925−1.0). Conclusions: Quantitative CT airway analysis in patients with DIPNECH demonstrates increased airway wall thickness and airway:artery ratio compared to controls. Advances in knowledge: Quantitative CT measurement of airway wall thickening offers a potential imaging biomarker for treatment response.

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.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH): Prevalence, clinicopathological characteristics and survival outcome in a cohort of 311 patients with well-differentiated lung neuroendocrine tumours

INTRODUCTION

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is considered to be a rare condition associated with lung neuroendocrine tumours (NET), and its natural history is poorly described. We aimed to assess the prevalence and clinicopathologic characteristics of DIPNECH in the lung NET population, and to investigate predictors of time-to-progression (TTP) and overall survival (OS).

METHODS

We retrospectively identified patients diagnosed with DIPNECH between April 2005 and December 2020. Clinical data were collected from medical records. The relationship between baseline characteristics and TTP and OS was analysed using the Kaplan-Meier method. Univariate analysis was performed using the Cox proportional hazards model.

RESULTS

Of 311 patients with well-differentiated lung NETs, 61 (20%) had DIPNECH and were included in the study. Baseline demographics described 95% female, 59% never smokers and mean body mass index 34.4 kg m^-2 ; 77% were typical carcinoids (TC), 13% atypical carcinoids (AC), and 10% both TC and AC (multicentric). At presentation, 54% of patients were asymptomatic. Multicentric NETs were demonstrated in 16 (26%) on histopathology, and a further 32 (52%) had synchronous NETs suggested on imaging (multiple nodules ≥ 5 mm). Seven (11%) patients developed metastases and the median OS from time of first metastasis was 37 months. AC histopathology and NET TNM stage ≥ IIA were associated with poorer TTP and OS. Of the DIPNECH cohort, the 15-year survival rate was 86%.

CONCLUSIONS

DIPNECH may be more prevalent in the lung NET population than previously appreciated, especially in women. Although our results confirm that DIPNECH is predominantly an indolent disease associated with TC, 23% developed AC and these patients may warrant closer observation.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia presenting as a solitary lung nodule: a rare histopathological diagnosis

We present a case of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) in a 56-year-old woman, who presented to our emergency department with a 7-day history of exertional dyspnoea. Due to profound haemodynamic compromise, pulmonary embolism (PE) was suspected, and the patient underwent emergency thrombolysis on admission. A subsequent computerized tomography pulmonary angiogram revealed extensive bilateral PE. Incidentally, a 1.3 cm lesion within the right upper lobe, associated with pleural tethering, was identified. Positron emission tomography computerized tomography and, subsequently, histopathology revealed this lesion to be primary DIPNECH, a rare pre-invasive hyperplasia of neuroendocrine cells. While studies are scarce and cohort numbers are low, somatostatin analogues and protein kinase inhibitors have been proven to reduce symptoms and increase progression-free survival in DIPNECH, respectively.

De-labeling severe asthma diagnosis: the challenge of DIPNECH

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare pulmonary disease characterised by neuroendocrine cell hyperplasia within the bronchial epithelium [1]. The clinical presentation is characterised by nonspecific respiratory symptoms such as chronic cough, dyspnoea and bronchospasm. Given the rarity of the disease and the low specificity of symptoms, the diagnosis of DIPNECH is challenging and the time between symptom onset and diagnosis is long [1]. DIPNECH comprises a generalised proliferation of scattered neuroendocrine cells, small nodules (neuroendocrine bodies) or a linear proliferation of pulmonary neuroendocrine cells. It has been suggested that DIPNECH may mimic [2] or precede [3] asthma. The role of products of neuroendocrine cells such as substance P, which contribute to eosinophil migration, has been suggested to explain asthma symptoms in DIPNECH [3]. However, the characteristics of patients with DIPNECH who have symptoms suggestive of asthma have never been described. The aim of our study was to determine whether patients diagnosed with DIPNECH and initially referred for severe asthma management had specific characteristics.

DIPNECH is a differential diagnosis of severe asthma with no specific biomarkers. Chronic cough and multiple nodules on CT should prompt clinicians to consider this diagnosis. Differentiating DIPNECH from severe asthma remains crucial.https://bit.ly/3mmFbQn

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia: clinical characteristics and progression to carcinoid tumour

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is considered a preinvasive lesion that may progress to carcinoid tumour [1]. Histologically, it is marked by a proliferation of neuroendocrine cells that is confined to the basement membrane (neuroendocrine cell hyperplasia; NECH), and/or has invaded past the basement membrane (carcinoid tumourlet) [2]. Tumourlets equal to or larger than 5 mm are classified as carcinoid tumours. Per the World Health Organization 2021 criteria, DIPNECH can be pathological (based solely on characteristic histological features) or clinical (diagnosed per characteristic symptoms and imaging findings, e.g. respiratory symptoms, bilateral pulmonary nodules, mosaic attenuation on computed tomography (CT)) [2]. In contrast to some lung diseases or neoplasms that can cause secondary, reactive NECH/tumourlets to form, DIPNECH is marked by such hyperplasia without an identifiable cause.

DIPNECH is a rare disease that is often misdiagnosed. In this study, it primarily affected elderly white women who were non-smokers. Lung nodules could slowly progress over years to carcinoid tumours. Average growth rate per nodule was 0.8 mm per year.https://bit.ly/3q1HD1k

A 72-Year-Old Woman With Multiple Pulmonary Nodules and a History of Malignancy

A 72-year-old woman, nonsmoker, presented with approximately 2 months of nonproductive cough. The cough was initially intermittent, occurred more regularly during bedtime, but gradually became more frequent throughout the day with no reported triggering factors. The remaining review of associated symptoms was negative; she did not complain of shortness of breath, fever, chest pain, muscle weakness, weight loss, night sweats, or fatigue. She previously had been given a prescription of butamirate syrup and decongestant nasal spray with no response. Her medical history included successfully treated papillary thyroid cancer with total thyroidectomy 4 years ago, and there was no need for further therapy. Patient was free of disease on follow up from her endocrinologist, to optimize levothyroxine treatment. Her regular prescription included statins. Her professional occupation was not related to special exposure, and she reported no alcohol consumption, illicit drug use, or any recent travel.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia: DIPNECH

PURPOSE OF REVIEW

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare premalignant condition. Over the past decade, there has been increased recognition and reporting of DIPNECH in the literature. Currently, our understanding is that DIPNECH has a predilection to nonsmoking females around their sixth decade of life. The patients usually present with chronic cough, dyspnea, and computed tomography (CT) showing multifocal pulmonary nodules with associated mosaic attenuation. The clinic history is largely driven by constrictive obliterative bronchiolitis, which typically has an indolent course with progressive respiratory decline and difficult to treat symptoms.

RECENT FINDINGS

DIPNECH has been found to be associated with carcinoid tumors. Recent data has found that symptomatic DIPNECH patients respond to somatostatin analog (SSA). SSAs provide improvement in symptoms and pulmonary function tests. According to small studies and case series SSAs can be used in conjunction with steroids and bronchodilators for the treatment of respiratory symptoms.

SUMMARY

DINPNECH is a premalignant condition that can transform into carcinoid tumors. Although the recent data suggest the potential efficacy of SSA, further studies are needed to validate such results in prospective fashion in addition to investigating other therapeutic agents.

An Update on the Management of Diffuse Idiopathic Pulmonary Neuroendocrine Cell Hyperplasia (DIPNECH)

OPINION STATEMENT

DIPNECH is caused by an idiopathic proliferation of pulmonary neuroendocrine cells which can lead to bronchiolitis and multifocal lung neuroendocrine tumors. Patients often present with chronic cough and dyspnea. Larger NETs may develop malignant potential. Somatostatin analogs can palliate chronic symptoms, particularly cough. Surgical resection can be considered for relatively large (e.g. >1 cm), progressive tumors.

Constrictive bronchiolitis in diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Background

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is characterised by multifocal proliferation of neuroendocrine cells and belongs in the spectrum of pulmonary neuroendocrine tumours. Some patients with DIPNECH develop airflow obstruction but the relationship between the two entities remains unclear.

Methods

We performed a computer-assisted search of the Mayo Clinic's electronic medical records for biopsy-proven cases of DIPNECH. We extracted clinical, pulmonary function, imaging and histopathological data along with treatments and outcomes.

Results

Among 44 patients with DIPNECH 91% were female and the median age was 65 years (interquartile range 56–69 years); 73% were never-smokers. Overall, 38 patients (86%) had respiratory symptoms including cough (68%) and dyspnoea (30%); 45% were previously diagnosed to have asthma or COPD. Pulmonary function testing showed an obstructive pattern in 52%, restrictive pattern in 11%, mixed pattern in 9%, nonspecific pattern in 23%, and was normal in 5%. On chest computed tomography scan, 95% manifested diffuse nodules and 77% manifested mosaic attenuation. For management, 25% of patients were observed without pharmacological therapy, 55% received an inhaled bronchodilator, 41% received an inhaled corticosteroid, 32% received octreotide; systemic steroids, azithromycin, or combination chemotherapy was employed in four patients (9%). Of 24 patients with available follow-up pulmonary function tests, 50% remained stable, 33% worsened and 17% improved over a median interval of 21.3 months (interquartile range 9.7–46.9 months).

Conclusion

DIPNECH occurs mostly in women and manifests diffuse pulmonary nodules and mosaic attenuation on imaging. It is commonly associated with airflow obstruction due to constrictive bronchiolitis, which manifests limited response to current pharmacological therapy.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an under-recognised cause of obstructive lung disease in women. Constrictive bronchiolitis associated with DIPNECH manifests limited response to currently employed therapies.https://bit.ly/3c3RZoe