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Introduction: Pulmonary arteriovenous malformations (PAVM) present with a variety of clinical manifestations, including hemoptysis. The usual management strategy relies upon interventional techniques, with surgery reserved for cases which are recalcitrant to less invasive measures. Case presentation: A 14-year-old female presented with massive and refractory hemoptysis. CTA and bronchoscopy did not identify a targetable lesion, but given her clinical instability she underwent percutaneous angiography which identified a right-sided PAVM with bronchial artery to pulmonary artery communication coursing near the right mainstem bronchus. Embolization procedures were initially successful to control bleeding, but recurrences of hemoptysis prompted surgical evaluation. Approximately two years after initial presentation, we performed robotic ligation of her PAVM which resulted in definitive control of the lesion with no additional bleeding episodes. She recovered well from surgery with a one-night hospital stay, and has experienced no surgical complications or recurrent bleeding to date. Conclusion: Rarely, pediatric PAVMs may require surgical intervention if interventional methods do not achieve definitive therapy. A variety of surgical techniques may be employed as dictated by the lesion's characteristics. Robotic approaches, including ligation, should be considered for patients with failure of conservative measures as it provides minimally invasive, precise technical management of PAVM.

Herein, we present a rare, although important complication of central venous access in pediatric surgery. Upon exchange of a port, this patient was found to have a calcified fibrin sheath that had embolized into the right pulmonary artery system. Initially, this diagnosis was unclear as it was thought to have been a fractured portion of the catheter. Thus, the patient required multiple diagnostic studies, including a cardiac catheterization to make the final diagnosis. Ultimately, she was treated with anticoagulation and did well. This report highlights the imaging findings of this complication, the diagnostic dilemma it creates, the potential significant consequences, as well as one approach of managing patients with an embolized fibrin sheath from a central venous catheter.

Summary: Regenerative paradigms exhibit nerve dependency, including regeneration of the mouse digit tip and salamander limb. Denervation impairs regeneration and produces morphological aberrancy in these contexts, but the direct effect of innervation on the stem and progenitor cells enacting these processes is unknown. We devised a model to examine nerve dependency of the mouse skeletal stem cell (mSSC), the progenitor responsible for skeletal development and repair. We show that after inferior alveolar denervation, mandibular bone repair is compromised because of functional defects in mSSCs. We present mSSC reliance on paracrine factors secreted by Schwann cells as the underlying mechanism, with partial rescue of the denervated phenotype by Schwann cell transplantation and by Schwann-derived growth factors. This work sheds light on the nerve dependency of mSSCs and has implications for clinical treatment of mandibular defects. : Jones et al. demonstrate the nerve dependency of mandibular bone repair after degeneration of the inferior alveolar nerve. Schwann cell paracrine signaling is required for skeletal stem cell enactment of bone healing. Rescue of healing by Schwann cell transplantation highlights skeletal stem cell-Schwann cell circuitry during mandibular repair. Keywords: skeletal stem cells, Schwann cells, mandibular repair, nerve-dependent mandibular regeneration