Solitary Metastatic Destruction of the Left Sternoclavicular Joint in a Patient with Triple-Negative Breast Cancer: A Case Report & Review of literature
Dr. M. A. Naseer *1, Dr Gagan Deep Singh 2, Mr. Prashant Patiyal 3, Dr Ansar 4
1. Department of Radiation Oncology, Surjit Multispecialty & Cancer Hospital, Amritsar, Punjab.
2,3,4. Surjit Multi Speciality and Cancer Hospital.
*Correspondence to: Dr. M. A. Naseer, Department of Radiation Oncology, Surjit Multispecialty & Cancer Hospital, Amritsar, Punjab.
Copyright
© 2026 Dr. M. A. Naseer is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 11 June 2026
Published: 01 July 2026
DOI: https://doi.org/10.5281/zenodo.21069790
Abstract
Background: Solitary metastasis to the sternoclavicular joint (SCJ) is an exceedingly rare presentation of breast cancer. Triple-negative breast cancer (TNBC) is known for its aggressive biology and early recurrence.
Case Presentation: A 50-year-old female with treated pT2pN1Mx right-sided TNBC presented 16 months post-surgery with a suprasternal swelling. Imaging (CE-CT/PET- CT) revealed a solitary, FDG-avid lytic destructive lesion of the left manubrium and clavicular head with soft tissue swelling over the bone. Despite inconclusive biopsy, clinical history led to the diagnosis of solitary bone metastasis.
Conclusion: Isolated SCJ involvement in TNBC is very rare and mimics localized inflammatory conditions. Clinicians should maintain high degree of suspicion for unusual bony recurrences in TNBC, which require localized palliative radiotherapy for skeletal stability & good pain control.
Keywords: Triple-negative breast cancer, sternoclavicular joint, bone metastasis, lytic lesion, palliative radiotherapy.
Introduction
Triple-negative breast cancer (TNBC) lacks estrogen, progesterone, and HER-2 receptor expression, correlating with high recurrence rates and poor prognosis[1, 2, 3]. While bone is a frequent site for breast cancer metastasis, the sternoclavicular joint (SCJ) is rarely involved in isolation (<5%) [4]. We present a unique case of metachronous solitary lytic metastasis to the contralateral SCJ following standard multimodal treatment for TNBC.
Case Presentation
A 50-year-old female was diagnosed with invasive ductal carcinoma of the right breast in August 2024. She underwent breast-conserving surgery (BCS) and axillary lymph node dissection. The pathology revealed 2.5x2x2cm, grade 2 triple negative breast cancer. 2/12 axillary lymph nodes were involved. She received dose dense adjuvant chemotherapy AC followed by Docetaxel completed in March 2025.This was followed by adjuvant VMAT radiotherapy to the right breast/SCF (45 Gy/25 fractions) with a 12 Gy boost, completed in May 2025.
The patient presented in December 2025, with a palpable, firm suprasternal swelling. CE-CT on December 27 revealed lytic destruction of the manubrium sternum and left clavicular head with an associated soft tissue mass (Image 1). PET-CT (December 29) showed no systemic disease except for an FDG-avid destructive lesion at the left SCJ and 1st left costo-chondral junction (Image 2).
FNAC and core biopsy were performed but remained inconclusive due to the dense stromal reaction. Based on the aggressive clinical history and radiographic evidence, the patient was treated with palliative radiotherapy (3D-CRT) using a 5mm bolus for surface build up (January–February 2026) (Image 3). She achieved significant subjective symptom relief & is disease free when last seen in March 2026.
Discussion
Solitary sternal or clavicular metastasis is rare, with isolated sternal involvement typically occurring in only 2.4% of bone-only metastases[4]. The contralateral location in this patient suggests a haematogenous route of spread rather than direct lymphatic extension. TNBC exhibits a distinct metastatic pattern; while visceral spread is common, skeletal lesions are predominantly lytic and aggressive, often presenting within 24 months of initial diagnosis [1, 2].
Biopsy of bone lesions remains a diagnostic challenge, with up to 25% of samples being non-diagnostic[5, 6 & 7]. In the setting of high-risk TNBC, functional imaging (PET-CT) is highly sensitive for identifying these early lytic destructions[5]. Palliative radiotherapy remains the gold standard for management, effectively stabilizing bone and providing pain relief in 60–80% of patients [8 & 9].
Conclusion
This case highlights the importance of recognizing the SCJ as a potential site for solitary TNBC metastasis. Early identification of these lesions is crucial for initiating local treatments that maintain quality of life and skeletal integrity.
References