Bilateral lower extremity inflammatory lymphedema in Air Force basic trainees: clinical and epidemiologic study of a new disease entity.

IMPORTANCE This observational study characterizes a new clinical condition identified in 55 military trainees. OBJECTIVE To determine the incidence and underlying cause of bilateral lower extremity inflammatory lymphedema in Air Force basic trainees. DESIGN, SETTING, AND PARTICIPANTS An observational study was conducted at Lackland Air Force Base in San Antonio, Texas. Participants included 14 243 Air Force basic trainees who entered training between September 2011 and January 2012 and the 55 trainees (0.4%) who developed bilateral lower extremity inflammatory lymphedema that occurred during the 8½-week basic training course. Two modifiable risk factors were evaluated: vaccine reaction and newly issued military footwear (combat boots and boot socks). INTERVENTIONS During November 2011, all new trainees wore only white socks and running shoes rather than the issued military footwear. During December 2011 and January 2012, the scheduled administration of tetanus/diphtheria/acellular pertussis and meningococcal vaccines, respectively, was delayed by 1 week for all new trainees. A full medical record review was conducted for every confirmed case of bilateral lower extremity inflammatory lymphedema. MAIN OUTCOMES AND MEASURES Identification of incident cases, symptom onset, antimicrobial treatment, immunization reaction, laboratory studies, specialty referral, and biopsy. RESULTS Fifty-four of the 55 incident cases (98%) of bilateral lower extremity inflammatory lymphedema occurred during the first 120 hours of training. Alterations in the timing of the military footwear used and selected vaccine administration had no effect on the incidence of new cases. Two participants (4%) experienced symptom onset before receipt of the vaccines. Oral antimicrobial medications were not found to speed symptom resolution compared with conservative treatment measures (P = .34). One incident case was diagnosed as leukocytoclastic vasculitis by tissue examination. CONCLUSIONS AND RELEVANCE Multiple training-related risk factors were ruled out as sources of bilateral lower extremity inflammatory lymphedema. Cases are likely secondary to prolonged standing with resultant gravity-dependent venous congestion and inflammatory vasculitis. The potential roles of undiagnosed venous reflux disease and the military physical training environment in these cases remain to be elucidated.