Hypertrophic pulmonary osteoarthropathy, secretory diarrhea and pancoast syndrome in the setting of a large cell neuroendocrine carcinoma of the lung: A case report

Large cell neuroendocrine carcinoma of the lung is a rare and aggressive pulmonary malignancy. Given its peripheral location, patients are frequently asymptomatic at the time of diagnosis or present with non-specific complaints. Moreover, its association with paraneoplastic syndromes or structural intrathoracic complications are highly atypical. Here, we report a case involving a 57-year-old female who presented with two simultaneous paraneoplastic syndromes, including hypertrophic pulmonary osteoarthropathy and secretory diarrhea, prior to the diagnosis of an early-stage large cell neuroendocrine carcinoma of the lung. Both syndromes showcased rapid symptomatic resolution following tumor resection. Upon disease recurrence, the patient developed a presentation consistent with Pancoast syndrome, with gradual improvement following the initiation of chemoradiotherapy. Individually, these conditions are rarely reported in association with large cell neuroendocrine carcinoma of the lung making their combination highly unusual. Furthermore, related symptoms were present both before and at the time of diagnosis, and upon disease recurrence. This highlights the importance of maintaining a high clinical suspicion for atypical manifestations of malignancy.