Development of DIPNECH (Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia) complicating multiple pulmonary metastases of a pelvic osteosarcoma

Introduction: Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an exceptional disorder and information on the course of this entity is limited. Only a small number of cases have been described in the literature. However, it has become recognized that DIPNECH is a precursor lesion to pulmonary carcinoid tumors that make up to 2% of all lung tumors.

Case presentation: A 71-year-old female presented with a pelvic osteosarcoma and multiple bipulmonary nodules (n >30). Following neoadjuvant treatment with 6 cycles of chemotherapy (EURO-BOSS) surgery of the pulmonary metastases and the primary tumor was planed. A re-staging CT scan revealed only three suspect lesions in the left and five in the right lung remaining. The patient underwent bilateral sequential antero-lateral thoracotomy with systematic digital examination and enucleation of 9 lesions on the left side and 12 on the right side. Interestingly, histopathology revealed only 3 metastases, 6 non-malignant lesions and 12 DIPNECH lesions. A comparison of the preoperative CT scan and the resected areas confirmed that both DIPNECH and metastases had been detected. However, they could not be discriminated, neither a priori nor post-hoc.

Conclusions: This rare case demonstrates evidence of DIPNECH parallel to pulmonary metastatic disease before and even under chemotherapy treatment. The neuroendocrine lesions mimicked metastasis of the sarcoma and interfered with the oncological treatment.