When supportive care backfires: G-CSF induced aortitis unmasked during routine adjuvant chemotherapy

Abstract Case Summary: In today's fast-paced oncology world, where patient volume is only increasing, the ability to recognize rare but serious treatment side effects is more important than ever. We present an interesting case of a 52-year-old female patient recently diagnosed with clinical Stage IIA, ER-positive/PR-positive, HER2-negative right breast cancer. Patient underwent a right lumpectomy with axillary sentinel lymph node biopsy, revealing a final pathological stage of pT1Nmi with micro metastatic invasive ductal carcinoma and Oncotype DX score of 33. After shared decision-making, patient began monthly adjuvant docetaxel/cyclophosphamide (TC) chemotherapy with G-CSF (Neulasta) support. Following the third cycle of chemotherapy, patient received G-CSF as per protocol. Six days later, patient presented to the ER with acute onset chest pain. She was noted to be tachycardic with a HR of 111 and ECG showing sinus tachycardia. Lab work showed normal troponin and elevated inflammatory markers (CRP 105, ESR 51). CTA Chest ruled out pulmonary embolism but revealed periaortic fat stranding near the aortic arch. Given this finding, a broad infectious and vasculitis workup was initiated. All results including blood cultures, ANCA, p-ANCA, atypical p-ANCA, RVP, and syphilis testing were negative. The patient improved dramatically with Prednisone 60mg once while hospitalized and discharged with a prolonged Prednisone taper. A diagnosis of G-CSF-induced aortitis was made based on the timing, exclusion of alternative etiologies, and therapeutic response. Clinical Decisions & Outcomes: Steroids led to rapid symptom relief and down-trending inflammatory markers (CRP dropped from 105 to 73). Given the presumed diagnosis of G-CSF-induced aortitis and the patient's high Oncotype score, the oncology team faced a tough but necessary decision: chemotherapy was discontinued, and the patient proceeded with radiation and hormone therapy. This case prompted awareness within the care team about recognizing inflammatory complications post-G-CSF. It reinforced the importance of multidisciplinary collaboration with oncology, infectious disease, radiology, and hospital medicine in managing diagnostic uncertainty and avoiding unnecessary interventions. Early recognition of G-CSF induced aortitis hinges on a high index of suspicion within the 5 to 7-day window after administration, as patients may present with fever, chest pain, and markedly elevated inflammatory markers. Embedding red-flag alerts for supportive-care toxicities into triage protocols and providing regular multidisciplinary training can streamline care pathways, reduce emergency visits, and safeguard both patient outcomes and provider well-being in high-volume cancer centers. Conclusion: This case highlights how early recognition of rare treatment-related toxicities, even those tied to supportive agents like G-CSF can change the clinical trajectory and spare patients from unnecessary testing or prolonged hospitalization. Embedding red-flag symptom pathways into triage protocols, especially in high-volume cancer centers, is a practical and scalable way to protect care quality. When multidisciplinary teams are empowered with education and diagnostic curiosity, even rare complications don't stand a chance of being missed.