ABSTRACT
INTRODUCTION AND IMPORTANCE: Fractures in the proximal tibial tuberosity are rare injuries. Even more uncommon are bilateral simultaneous fractures. Due to the few cases reported in the literature, we aimed to present a case which may contribute to the diagnosis and treatment of bilateral simultaneous tibial tubercle fractures. CASE PRESENTATION: A 13-year-old Hispanic male presented to the emergency department after experiencing sudden knee buckling while running after standing up from the catcher's position (squatted) during a baseball game, causing him to collapse to the ground. Plain radiographs revealed displaced tibial tubercle avulsion fractures in both knees. He underwent bilateral open reduction and internal fixation. Fracture healing was completed without complications. DISCUSSION: To the best of our knowledge, this is the first documented case of a Hispanic pediatric baseball player, adding to the small number of reported cases of bilateral tibial tubercle fractures. The presented case is rare in terms of the mechanism of injury, which has been scantly reported in the literature. CONCLUSION: Due to the rarity of atraumatic bilateral tibial tubercle fractures we believe this documentation may be of clinical relevance.
ABSTRACT
Among the different immune cells present within tumors, B cells also infiltrate human papillomavirus-positive (HPV+) oropharyngeal tumors. However, the role of B cells during programmed death-1 (PD-1) blockade in HPV+ oropharyngeal cancer needs to be better defined. By using the preclinical mouse model for HPV+ oropharyngeal cancer (named mEER), we characterized B cells within tumors and determined their functional role in vivo during PD-1 blockade. We determined that treatment naïve tongue-implanted tumors, which we have previously demonstrated to be sensitive to PD-1 blockade, contained high infiltration of CD8+ T cells and low infiltration of B cells whereas flank-implanted tumors, which are resistant to PD-1 blockade, contain a higher frequency of B cells compared to T cells. Moreover, B cell-deficient mice (µMt) and B cell-depleted mice showed a slower tumor growth rate compared to wild-type (WT) mice, and B cell deficiency increased CD8+ T cell infiltration in tumors. When we compared tongue tumor-bearing mice treated with anti-PD-1, we observed that tumors that responded to the therapy contained more T cells and B cells than the ones that did not respond. However, µMt mice treated with PD-1 blockade showed similar tumor growth rates to WT mice. Our data suggest that in untreated mice, B cells have a more pro-tumorigenic phenotype potentially affecting T cell infiltration in the tumors. In contrast, B cells are dispensable for PD-1 blockade efficacy. Mechanistic studies are needed to identify novel targets to promote the anti-tumorigenic function and/or suppress the immunosuppressive function of B cells in HPV+ oropharyngeal cancer.