Hormonal receptor positive human epidermal receptor 2 negative (HR⁺/HER2^-) is the commonest molecular subtype of breast cancer (BC). Patients with HR⁺/HER2^- BC may manifest clinically a late recurrence whose BC metastasizes 10-15 years post-operatively. We report one case who presented with pulmonary mass in upper lobe of lung and Horner syndrome 16 years after BC surgery. FDG PET/CT suggested pulmonary malignancy but could not differentiate between primary or metastatic cancer when invasive biopsy was quite risky. Novel ¹⁸F-FES PET/CT facilitated the non-invasive functional diagnosis of estrogen-receptor positive (ER+) pulmonary metastasis of BC, and the patient experienced partial response (PR) after CDK4/6 inhibitor and aromatase inhibitor as endocrine therapy. This article reviews the diagnosis and treatment process of this case, to provide guidance for non-invasive global evaluation of ER status among metastatic HR⁺/HER2^- BC patients with ¹⁸F-FES PET/CT.

Phosphatase and tensin-homolog deleted on chromosome 10 (PTEN) is an important cancer suppressor gene. Its pathogenic mutation leads to PTEN hamartoma tumor syndrome (PHTS), a rare syndrome also known as Cowden syndrome, which is relevant to early-onset hereditary breast cancer (BC). In this paper, we report three patients with unilateral multicentric BC and synchronous and metachronous bilateral BC who harbored PTEN gene mutations, and summarize the clinical manifestations, pathological characteristics, diagnosis, treatment and follow-up outcomes to provide reference for management of PTEN gene mutation-related BC among the Cowden syndrome population.