case_images: PMC10663045_01
case_images: Histology slides, immunohistochemistry staining of initial tumor ,and metastasis primary tumor samples (a, d, g) versus iliac bone metastasis (b, e, h) and liver metastasis (c, f, i). Stained for HE (a-c), estrogen receptors (d-f), and HER2 (g-i), showing a score of 2+ (g, h) (negative by FISH, not shown), and a score of 1+ (i). Scale bar: 100 mum, objective used x20. HE, hematoxylin and eosin; FISH, fluorescence in situ hybridization.
case_images: cro-2023-0016-0001-534572_F01.jpg
case_images: PMC10663045_01_cro-2023-0016-0001-534572_F01.jpg
case_images: F1
case_images: A 44-year-old female patient was diagnosed with right-sided multicentric stage IA invasive BC of no special type (NST), grade 2, estrogen receptor 80%, progesterone receptor 60%, HER2 negative (Fig. 1), and Ki67 30%. At three different time points (initial diagnosis, bone metastasis at recurrence, and liver metastasis) during the entire metastatic disease course, the patient underwent tumor tissue analyses each time a HER2-low endocrine-sensitive status was observed (Table 1; Fig. 1).
case_images: Baseline and follow-up brain MRI baseline brain MRI (top line, a, b) demonstrated diffuse vividly enhancing dural thickening (orange arrows) on axial (a) and sagittal (b) post-contrast gradient-echo 3D T1-weighted images. Two focal nodular lesions along the anterior and posterior falx (c, orange stars) were considered potential dural metastases or meningiomas, and a nodular enhancing lesion in the vermis corresponded to brain metastasis (orange arrowhead). At the 3-month follow-up brain MRI (bottom line), pachymeningeal thickening significantly decreased from 6 to 3 mm (white arrows) in either the axial (d) or sagittal (e) planes. The dural nodules and vermian metastases are stable in size (f, white arrowhead). The response was stable at a 6-month follow-up brain MRI (not shown). MRI, magnetic resonance imaging.
case_images: cro-2023-0016-0001-534572_F02.jpg
case_images: PMC10663045_01_cro-2023-0016-0001-534572_F02.jpg
case_images: F2
case_images: T2-weighted, spin echo, and gradient echo 3D-T1 weighted post-gadolinium, was performed according to current recommendations. These investigations revealed multiple small CNS metastases and dural thickening corresponding to meningeal metastasis (Fig. 2). After nearly 12 months of treatment, corresponding to 17 cycles, the patient continued her treatment with a partial response of the CNSm, with a significant decrease in meningeal thickness (Fig. 2).
case_images: 18F-FDG PET/CT maximal intensity projection (MIP). Before (a) and after (b) treatment with trastuzumab-deruxtecan showing metabolic response.
case_images: cro-2023-0016-0001-534572_F03.jpg
case_images: PMC10663045_01_cro-2023-0016-0001-534572_F03.jpg
case_images: F3
case_images: The systemic lesions regressed rapidly, except for two muscular lesions controlled with localized targeted radiation (Fig. 3).
case_images: Chronology of the patient's medical history. LM, leptomeningeal.
case_images: cro-2023-0016-0001-534572_F04.jpg
case_images: PMC10663045_01_cro-2023-0016-0001-534572_F04.jpg
case_images: F4
case_images: The chronology of the patient's medical history is summarized in Figure 4.