C77-29 Dipnech and Pulmonary Carcinoid Tumors in New Mexican Veterans: Distinct Clinical and Environmental Patterns

Pulmonary carcinoid tumors are uncommon, mostly indolent well-differentiated neuroendocrine neoplasms. A subset of these patients have diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH), a WHO-recognized preneoplastic lesion defined by diffuse neuroendocrine proliferation and distinct radiologic patterns, most often in older nonsmoking women. Reactive neuroendocrine hyperplasia (NEH) instead reflects secondary airway injury or hypoxia often found in smokers, though a causal link to tumorigenesis remains unproven.In a New Mexican Military Veteran cohort, we observed an increased number of pulmonary carcinoid tumors recently. It is possible that on top of common military service-related exposures, these patients face a distinct environmental context including a legacy of carcinogenic uranium mining and consequent elevated groundwater levels, elevated background radiation and altitudes which may compound military related toxic exposure and pulmonary injury. We hypothesize two etiologic pathways: DIPNECH associated carcinoids are primarily driven by intrinsic/genetic programs whereas solitary carcinoids may be associated with cumulative occupational and environmental lung damage. We retrospectively reviewed seven pulmonary carcinoid cases diagnosed by Interventional Pulmonology and Thoracic Surgery at the New Mexico VA (Jan 2021–Oct 2025), assessing demographics, service history and related exposures, comorbidities, prior lung cancer, PFTs, tumor features, altitude, and residential proximity to EPA national priority uranium sites. Variables were stratified by DIPNECH status and compared using Welch’s t and Fisher’s exact tests.Among seven veterans (five men, two women), two DIPNECH associated and five solitary pulmonary carcinoid tumors were identified. All were older veterans with typical histology. Solitary tumors arose in right lower lobe, whereas DIPNECH lesions localized to right middle and upper lobes. DIPNECH cases had lower tobacco exposure (2.5 vs 14.8 pack years, p = 0.32) and higher midflow rates (FEF25-75 = 102% vs 73%, p=.21). They resided farther from the nearest uranium mine (100 vs 51km, p = 0.10) yet in counties with slightly higher uranium concentrations (37.1 vs 31.7 ug/L, p=.26). COPD/asthma only occurred in solitary tumor cases, whereas pneumoconiosis appeared in DIPNECH patients, other variables were comparable. Although small sample limits inference, distinct patterns emerged. DIPNECH cases showed preserved mid-flow rates, minimal tobacco exposure and upper/middle lobe distribution, whereas solitary carcinoids clustered in the right lower lobe with greater smoking history, obstructive disease and small airway impairment. DIPNECH patients lived farther from uranium mines but in counties with higher groundwater uranium. These findings suggest potential exposure and biologic related distinctions that warrant validation in larger multi-institutional cohorts.