The neuroendocrine proliferations and tumors of the lung represent a broad clinical and pathologic spectrum and have particular imagen features.
The prognosis and outcome depends of its adecuate classification,
for this reason we describe the spectrum and their clinical,
pathologic,
and imaging findings.
Three manifestations of neuroendocrine cell proliferations have been described that occur in different clinical settings: reactive neuroendocrine cell hyperplasia with associated lung disease, neuroendocrine cell proliferations associated with carcinoid tumors,
and diffuse idiopathic neuroendocrine cell hyperplasia.
Reactive neuroendocrine cell hyperplasia associated with diseased lung is considered a response to chronic hypoxia and lung injury,
and it may be seen in patients with chronic bronchitis or emphysema.
Neuroendocrine cell proliferations have also been described in association with and adjacent to pulmonary carcinoid tumors.
In 1992,
a diffuse idiopathic form of neuroendocrine cell proliferations was formally recognized and defined,
which is currently known as diffuse idiopathic neuroendocrine cell hyperplasia.
Neuroendocrine neoplasms are tumors found throughout the body,
most commonly in the gastrointestinal tract followed by the thorax.
Neuroendocrine cells occur normally in the bronchial and bronchiolar epithelium and may be solitary or may occur in clusters.
Diffuse idiopathic neuroendocrine cell hyperplasia is a diffuse idiopathic form of neuroendocrine cell hyperplasia and is considered a preinvasive lesion that may give rise to carcinoid tumors,
it is presented in older women with chronic respiratory symptoms.
Carcinoid tumors are low-grade malignant neoplasms that affect symptomatic children and young adults.
Typical carcinoids are neoplasms with good prognosis,
atypical carcinoids are aggressive malignancies with a propensity for metastasis.
Treatment for both are complete surgical excision.
Large cell neuroendocrine carcinoma and small cell lung cancer are highly aggressive neuroendocrine malignancies that usually affect elderly smokers.
Patients may not be candidates for surgical resection,
are often treated with chemotherapy with or without radiation,
and have a poor prognosis.
Definitive diagnosis is usually made on the basis of findings from open lung or thoracoscopic biopsy.
Long-term follow-up is recommended for neuroendocrine neoplasm to exclude nodule growth and development of carcinoid tumors and/or lymph node metastases.
Pulmonary neuroendocrine neoplasms constitute approximately 20%–25% of all invasive primary lung cancers,
and the vast majority are small cell carcinomas.
The remaining neuroendocrine neoplasms combined represent 5% of primary lung cancers.
Carcinoid tumors typically affect the gastrointestinal tract.
The respiratory tract is the second one affect.
Carcinoid tumors constitute approximately 1%–2% of primary lung cancers.
Most pulmonary carcinoid tumors are typical carcinoid,
and ap- proximately 10%–16% are atypical carcinoid.
The diagnosis of carcinoid tumor requires microscopic evaluation of tissue,
which can be obtained with bronchoscopy,
image-guided percutaneous needle biopsy,
or thoracotomy.
The treatment of carcinoid tumor is complete surgical resection.
Metastatic and unresectable tumors may be treated with chemotherapy,
immunotherapy,
or radiolabeled agents such as somatostatin analogs.