Diffuse idopathic pulmonary neuroendocrine hyperplasia (DIPNECH)

Clinical History

A 64-year-old female non-smoker was referred for CXR to investigate a longstanding cough. The CXR identified numerous nodules at that time and an increase in the nodularity and interstitial shadowing was seen on a CXR 5 years later.
CT performed 5.5 years later confirmed multiple nodules.

Imaging Findings

Initial CXR (Fig. 1), showed a few tiny nodules bilaterally and prominent bronchial markings. No follow up.
Subsequent CXR 5 years later (Fig. 2), showed an increase in the number of lung nodules and a CT was advised. No follow up.
HRCT since the most recent CXR showed small randomly distributed nodules/bronchial wall thickening/mosaic perfusion (Fig. 3, 4), which are the most common findings in this entity [1, 2]. No enlarged lymph nodes were present in the chest.

Whole body CT was performed to look for primary malignancy, which confirmed bilateral lung nodules—the largest measuring 8 mm in the left upper lobe—(Fig. 4) and mosaic perfusion (Fig. 4, 5). No thoracic lymphadenopathy.
Mammogram was also normal.

The patient was referred to the regional centre for open lung biopsy via video-assisted thoracic surgery (VATS) to characterise the bilateral lung nodules and possible primary malignancy.

Histology showed diffuse idiopathic pulmonary neuroendocrine hyperplasia (DIPNECH) (Fig. 6, 7).

Discussion

DIPNECH is a diagnosis of exclusion and is increasingly being recognised as a cause for multiple lung nodules, which were histologically confirmed in our case. Chronic cough in a female patient is the usual clinical scenario for DIPNECH [3].

It is standard practice to explore the possible primary malignancy in a patient with multiple lung nodules. Review of old imaging is helpful especially in knowing that there has been no past malignancy or any other medical condition that could explain multiple lung nodules.

Imaging showing small airway disease and lung nodules, which are present for a long time, should raise the possibility of an alternative diagnosis in a patient with no known malignancy.

Further imaging with octreotide/MIBG imaging is possible but probably not an established practice.

Histology confirmation is the gold standard. In this case pathology showed neuroendocrine cell hyperplasia within small airways and several carcinoid tumourlets present in a bronchiolocentric distribution and fibrosis. This was confirmed by positivity for neuroendocrine immunohistochemical markers (CD56, synaptophysin and chromogranin) and TTF1.

This is an important diagnosis to make as it is a precursor to lung carcinoid tumourlet, but currently there are no established guidelines for follow-up and treatment strategies vary, ranging from medical management with inhalers to lung transplant [4].

Take home message from this case is that in cases where multiple lung nodules are not secondaries from a known primary, a review of all old imaging and histology confirmation with biopsy could change things for the patient for the better.

Differential Diagnosis List

Final Diagnosis

Diffuse idopathic pulmonary neuroendocrine hyperplasia (DIPNECH)

URL:	https://eurorad.org/case/12392
DOI:	10.1594/EURORAD/CASE.12392
ISSN:	1563-4086