Obliterative bronchiolitis caused by multiple tumourlets and microcarcinoids successfully treated by single lung transplantation

Radiological-pathological correlation in diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH): imaging and histopathology

AIM

To review histologically confirmed diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) cases and carry out a detailed pathological-radiological correlation to see if computed tomography (CT) can be used to confidently identify DIPNECH.

MATERIALS AND METHODS

Twenty-three histologically confirmed DIPNECH patients in the shared database of two NHS Trusts were reviewed. CT images were reviewed by two independent radiologists, each of them with >10 years of experience in thoracic imaging. All histological specimens were reviewed by a single pathologist with >25 years of experience. The diagnosis of DIPNECH was made according to the current World Health Organization (WHO) definition included in the WHO 2015 classification of pulmonary tumours. The results on histology were compared to the presence of nodules and air trapping on CT. Demographic information and, when available, molecular imaging studies and pulmonary function tests were also considered.

RESULTS

There are prototypal clinical and radiological findings reflecting the presence of underlying histological DIPNECH: middle-aged women with multiple small and scattered nodules due to the clustering and proliferation of neuroendocrine cells. At least one larger, dominant, lung nodule reflecting a carcinoid tumour is very common and mosaic attenuation/air trapping is seen approximately in 50% of cases in inspiratory scans. Airflow obstruction is rarely associated with histological bronchial or peribronchial fibrosis, which suggests other mechanisms must be involved in its development.

CONCLUSION

CT can be used to predict pathological DIPNECH in the appropriate clinical setting. It is important to consider DIPNECH to avoid overdiagnosis of more sinister conditions such as lung cancer or metastases.

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.

Diffuse idiopathic neuroendocrine cell hyperplasia as a rare cause of chronic cough

A 39-year-old Caucasian woman, who has never smoked, presented a 16-year-duration chronic dry cough. She was prescribed by her general physician with corticosteroid and long-acting β-agonist inhalers assuming it was asthma, with mild symptomatic improvement. When cough got more persistent and associated with exertional dyspnoea and wheezing, a chest CT scan was performed, which showed multiple bilateral micronodular formations and diffuse mosaic lung pattern with air trapping. She was sent to our Respiratory Department and performed a bronchoalveolar lavage and cryobiopsy that were inconclusive. She underwent surgical lung biopsy with pathology revealing multiple foci of neuroendocrine cell hyperplasia and tumourlets associated with constrictive bronchiolitis, a histological pattern suggestive of diffuse idiopathic neuroendocrine cell hyperplasia (DIPNECH). DIPNECH is a rare and preinvasive disease. Presenting symptoms can be cough and breathlessness. At the time of writing, the patient is on octreotide with symptomatic improvement.

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.

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

We report a case of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH). We performed immunohistochemical analysis of 17 neuropeptides and human gonadotropin-alpha (hCGα), a trophoblastic peptide that promotes the proliferation of neuroendocrine cells. A 51-year-old woman with no history of smoking was found to have a nodule in the right middle lobe. Upon examination, the nodule was found to comprise diffuse linear and nodular neuroendocrine cell hyperplasia (NECH), numerous pulmonary tumorlets merging with one peripheral carcinoid, and an additional central carcinoid. Immunohistochemical analysis revealed diffuse but intense expression of the general neuroendocrine markers CD56, synaptophysin, and chromogranin A, together with gastrin-releasing peptide (GRP), calcitonin, and hCGα throughout the carcinoids, tumorlets, and NECH. Positive staining was also noted for adrenocorticotropic hormone, corticotropin-releasing hormone, met-enkephalin, vasoactive intestinal polypeptide, neurotensin, and growth hormone-releasing hormone in a few isolated cells of the carcinoids and the tumorlets, but staining for these proteins was entirely negative in the NECH lesions. The presence of these neuropeptides in neuroendocrine tumors might explain the presence of neuropeptide-producing tumors of the lungs, cases of which have been reported over the last 30 years. The preoperative serum proGRP level was high but returned to normal after surgical intervention, indicating that GRP was produced and secreted by carcinoids, tumorlets, and/or NECH lesions. It is also probable that neuroendocrine cells secreted GRP into the interstitium in a paracrine manner, leading to the development of dense fibrosis around the tumorlets. During the preoperative and postoperative periods, no evidence of bronchiolitis obliterans was noted, in contrast to some previously reported cases of DIPNECH.

Surgical management of bronchopulmonary typical carcinoid tumors: an institutional experience

Bronchopulmonary typical carcinoid tumors are well known as low-grade malignant tumors with fairly benign behaviors; however, distant metastasis after complete resection and multiple carcinoid tumors in the resected lungs have been sporadically reported. Lesser resections are preferred including lung-sparing surgery, while the importance of major surgical resections is also emphasized. For better understanding of bronchopulmonary typical carcinoid tumors, we reviewed our institutional experience. Eight patients with bronchopulmonary typical carcinoid tumors underwent complete pulmonary resection. Various perioperative variables and postoperative survival were investigated retrospectively. All patients were alive after surgery. Seven patients received more than a lobectomy and one underwent a segmentectomy for a peripheral small nodule. In all patients, systemic nodal dissection was performed. In one patient who received a lobectomy for a peripheral nodule, multiple carcinoid tumors were found in the resected specimen. No patients received any adjuvant chemotherapy or radiotherapy after pulmonary resection. In one patient, tumors recurred at the bronchial stump and in the liver approximately five years after complete pulmonary resection. Despite a small number of cases, our study supported the idea that bronchopulmonary typical carcinoid tumors might require major surgical procedures and that complete pulmonary resection of typical carcinoid tumors could expect long-term survival.

Tumorlets, multicentric carcinoids, lymph-nodal metastases, and long-term behavior in bronchial carcinoids

BACKGROUND

The clinical significance of lymph-node metastases, multicentric forms, and tumorlets in bronchial carcinoids is still a matter of debate. Aim of this study was to analyze their prevalence and clinical significance in a series of 123 bronchial carcinoids.

PATIENTS AND METHODS

Nodal dissection and serial sections of resected lung parenchima for research of multicentric forms and tumorlets were performed in most patients. Survival curve was produced using the Kaplan-Meyer method and multivariate analysis by the Cox proportional hazard model.

RESULTS

Lymph-node involvement was present in 14% of typical (14 of 100) and 13.04% of atypical carcinoids (3 of 23). Multicentric forms (syncronous carcinoids or tumorlets) were found in 11.3% of the total with a negative impact on survival (p = 0.021). Multiple tumorlets were found in 7.3% of all cases at the standard pathologic examination, but whenever accurate palpation and serial sections of the surgical specimen were performed, the percentage reached 24% of the cases. Overall survival was 98.2%, 95.8%, and 83.9% for typical and 71.6%, 57.3%, and 24% for atypical carcinoid respectively at 5, 10, and 15 years. Time from surgery was significantly directly correlated with recurrences (p < 0.0001) and disease related death (p = 0.0002).

CONCLUSIONS

A high prevalence of tumorlets, multiple carcinoids, and lymph-nodal involvement was found in our series. On the basis of these observations bronchial carcinoids always require major surgical procedures with systematic nodal dissection, and a careful search for multifocal lesions should always be performed. Follow-up should always be accurate and protracted, due to the frequency of very long-term relapses (often more than 10 years after surgery).

Challenges in pulmonary fibrosis. 2: Bronchiolocentric fibrosis

Bronchiolocentric fibrosis is essentially represented by the pathological pattern of constrictive fibrotic bronchiolitis obliterans. The corresponding clinical condition (obliterative bronchiolitis) is characterised by dyspnoea, airflow obstruction at lung function testing and air trapping with characteristic mosaic features on expiratory high resolution CT scans. Bronchiolitis obliterans may result from many causes including acute diffuse bronchiolar damage after inhalation of toxic gases or fumes, alloimmune chronic processes after lung or haematopoietic stem cell transplantation, or connective tissue disease (especially rheumatoid arthritis). Airway-centred interstitial fibrosis and bronchiolar metaplasia are other features of bronchiolocentric fibrosis.

Significance of multiple carcinoid tumors and tumorlets in surgical lung specimens: analysis of 28 patients

BACKGROUND

The clinical significance of multiple carcinoid tumorlets in surgical lung specimens has not been systematically analyzed. We reviewed our experience to determine the range of clinical circumstances associated with this finding.

METHODS

We reviewed clinical records, available imaging, and pathology materials from patients evaluated at Mayo Clinic Rochester (from 1987 to 2000) with two or more carcinoid tumors or tumorlets in lung specimens.

RESULTS

Twenty-eight of 294 patients with a diagnosis of carcinoid tumor or tumorlet had two or more lesions. Twenty-six patients (93%) were women; mean age was 65 years. Patients were categorized into three groups: multiple nodules (n = 17), solitary lung nodules on preoperative imaging (n = 7), and airflow limitation (n = 4). Approximately half of patients with multiple nodules had respiratory complaints; two patients had Cushing syndrome. Ten patients (58.8%) were suspected of having pulmonary metastases, including 7 patients with previously diagnosed malignancies. Intrathoracic lymph node metastases were present in three patients, none of whom had recurrent disease. One patient had a carcinoid tumor resected 8 years later. Extrathoracic metastases developed in another patient 3 years after presentation, and the patient was alive with disease 2 years later. Only one patient with airflow limitation had a syndrome resembling diffuse idiopathic pulmonary neuroendocrine cell hyperplasia.

CONCLUSIONS

Our series represents the largest compilation of multiple carcinoid tumors or tumorlets. Our analysis reveals that multiple carcinoid tumors or tumorlets occur most commonly in patients with multiple nodules resembling metastatic disease. Significant airflow limitation is rare. Long-term survival is excellent, although patients have persistent disease.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia: an under-recognised spectrum of disease

AIMS AND METHODS

A review was undertaken of 19 patients diagnosed with diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) between 1992 and 2006.

RESULTS

Most patients were women (n = 15) and non-smokers (n = 16). Clinical presentation was either with symptomatic pulmonary disease (group 1; n = 9) or as an incidental finding during investigation for another disorder, most frequently malignant disease (group 2; n = 10). In group 1, cough and dyspnoea were the most frequent symptoms, with an average duration of 8.6 years before diagnosis. Both groups showed mainly stable disease without treatment, although one patient progressed to severe airflow obstruction and one was diagnosed at single lung transplantation. Mosaicism with nodule(s) was the typical pattern of DIPNECH on high-resolution computed tomography, but one case had normal imaging despite airflow obstruction. Lung function tests showed obstructive (n = 8), mixed (n = 3) or normal (n = 5, all group 2) physiology. Two patients underwent a bronchoalveolar lavage and showed a lymphocytosis (30%) with mild chronic bronchiolitis being seen in all biopsies. Tumourlets and associated typical carcinoids (n = 9) showed weak positivity for thyroid transcription factor-1. Three patients had atypical carcinoids, one with multiple endocrine neoplasia type 1 syndrome.

CONCLUSIONS

DIPNECH is being increasingly recognised, probably because of an increase in the usage and accuracy of investigative imaging and increased awareness of the entity. Most cases remain stable over many years independent of the mode of presentation, although a few patients progress to severe airflow obstruction.

Bronchiolar disorders

Bronchiolar abnormalities are relatively common and occur in a variety of clinical settings. Various histopathologic patterns of bronchiolar injury have been described and have led to confusing nomenclature with redundant and overlapping terms. Some histopathologic patterns of bronchiolar disease may be relatively unique to a specific clinical context but others are nonspecific with respect to either etiology or pathogenesis. Herein, we present a scheme separating (1) those disorders in which the bronchiolar disease is the predominant abnormality (primary bronchiolar disorders) from (2) parenchymal disorders with prominent bronchiolar involvement and (3) bronchiolar involvement in large airway diseases. Primary bronchiolar disorders include constrictive bronchiolitis (obliterative bronchiolitis, bronchiolitis obliterans), acute bronchiolitis, diffuse panbronchiolitis, respiratory bronchiolitis, mineral dust airway disease, follicular bronchiolitis, and a few other rare variants. Prominent bronchiolar involvement may be seen in several interstitial lung diseases, including hypersensitivity pneumonitis, respiratory bronchiolitis-associated interstitial lung disease, cryptogenic organizing pneumonia (idiopathic bronchiolitis obliterans organizing pneumonia), and pulmonary Langerhans' cell histiocytosis. Large airway diseases that commonly involve bronchioles include bronchiectasis, asthma, and chronic obstructive pulmonary disease. The clinical relevance of a bronchiolar lesion is best determined by identifying the underlying histopathologic pattern and assessing the correlative clinico-physiologic-radiologic context.

Obstructive lung diseases: COPD, asthma, and many imitators

Chronic obstructive pulmonary disease (COPD) is a common respiratory disorder that occurs in 10% to 15% of people who smoke, an estimated 16 million Americans. Asthma is also common. Spirometry is generally used to detect early COPD in smokers and to evaluate patients with respiratory symptoms. Although COPD and asthma account for most obstructive lung diseases, a broad spectrum of other disorders, including bronchiectasis, upper airway lesions, bronchiolar diseases, and some interstitial lung diseases, are associated with airflow obstruction. These less common forms of obstructive lung diseases are often misdiagnosed because of their uncommon occurrence and poor recognition. We describe the heterogeneous spectrum of disorders that can present with evidence of airflow obstruction and outline a diagnostic approach to obstructive lung disease.

Small airways diseases: detection and insights with computed tomography

Diseases affecting the small airways are difficult to detect by traditional diagnostic tests. Widespread involvement is needed before symptoms and abnormalities on pulmonary function testing or chest radiography become apparent. Obstruction of the bronchioles may be detected indirectly by computed tomography (CT) because regional under-ventilation results in reduced perfusion which in turn is shown as a mosaic attenuation pattern of the lung parenchyma. When there is inflammation of the bronchioles with accompanying exudate, the airways may become directly visible on CT, for example in cases of diffuse panbronchiolitis. Quantification of the various morphological features of small airways disease is possible from CT images and this increased precision has aided investigations of structure/function relationships. An understanding of the pathology and microscopic distribution of disease in relation to the airways allows some prediction of the likely computed tomography appearances in this wide spectrum of conditions, and thus helps to refine the differential diagnosis.

Multifocal peripheral bronchial carcinoid tumour

Peripheral bronchial carcinoids sometimes arise as single solid or nodular lesions in the periphery of the lung. We encountered a 74-year-old Japanese male with bronchial carcinoids that were widely disseminated throughout the lung parenchyma. Pulmonary function tests revealed mild airflow obstruction. A metastatic process was ruled out from primary malignancy and a histological examination revealed findings consistent with a peripheral bronchial carcinoid. Based on these findings, we concluded that this patient had a primary multifocal peripheral bronchial carcinoid. An immunohistochemical examination revealed immunoreactivity for chromogranin A and bombesin. The present case appears to be an unusual case of diffuse multifocal peripheral bronchial carcinoid, confirmed by immunohistochemistry.

Obstructive pulmonary disease. The clinician's perspective

This article reviews the differential diagnosis of obstructive lung disease, including lesions that may mimic chronic obstructive pulmonary disease, as well as the tools on which the clinician relies for making a proper diagnosis. The clinician's view of the radiologist's role is briefly discussed, but the details of specific radiologic techniques are discussed elsewhere in this issue.