DIPNECH presenting on a background of malignant melanoma: new lung nodules are not always what they seem.

The coexistence of lung nodules on a CT scan with worsening respiratory symptoms in the context of previous malignant melanoma would usually signify metastatic disease. The cause of the lung nodules in this 69-year-old woman turned out to be diffuse idiopathic neuroendocrine cell hyperplasia (DIPNECH) with tumourlets. DIPNECH is extremely rare, with fewer than 100 cases reported in the literature worldwide. The key to making this diagnosis was that the nodules were not avid on a positron emission tomography-CT scan, as would have been expected in metastatic melanoma. This led to a biopsy diagnosis. At the time of writing, the patient remains symptomatic with stable disease.