Ossified diagnosis: sarcoidosis masquerading as metastatic breast cancer

Abstract

A 40-year-old woman was referred to the Breast Unit with a solid lump in her right breast. Investigations revealed an invasive lobular carcinoma. The patient underwent a right-sided mastectomy and sentinel lymph node (LN) biopsy, which confirmed axillary LN involvement. The postsurgery staging CT showed unusual enlargement of mediastinal and hilar LN bilaterally. This was consistent with positron emission tomography/CT and MRI, which further established the presence of several bone lesions. Determining the pathology within the LN and bones was pivotal in providing an accurate diagnosis and deciding subsequent management. However, histopathological analysis of the initial endobronchial ultrasound-guided fine-needle aspiration biopsy of mediastinal LN failed to identify definitive metastatic breast cancer cells. The case was extensively discussed in several multidisciplinary team meetings. Collective evidence, including clinical presentation, comparative imaging analysis, and further biopsies confirmed sarcoidosis with bone involvement-mimicking metastatic disease.

Keywords: breast cancer; immunology; orthopaedics; radiology; respiratory medicine.

Figure 1

Invasive lobular carcinoma of the upper right breast on imaging. Architectural distortion and microcalcifications were shown in the upper right breast on medial lateral oblique and cranial caudal (CC) tomosynthesis (A and B) and CC mammography (C). Extensive suspicious non-mass enhancement was shown in the right breast on a maximum intensity projection of an axial dynamic contrast-enhanced T1-weighted MRI sequence at peak enhancement (D).

Figure 2

CT image of mediastinal region. Mediastinal and bilateral hilar lymphadenopathy chest (A) and rounded retroperitoneal lymph node (B) were shown on CT imaging.

Figure 3

PET/CT image of mediastinal region. Mediastinal, hilar and retroperitoneal lymphadenopathy (A and B) and multiple areas of increased ¹⁸F-FDG uptake in the bone (C and D) without corresponding bone lesions were visible in CT staging (E and F). ¹⁸F-FDG, fluorodeoxyglucose; PET/CT, positron emission tomography/CT.

Figure 4

Bone marrow alterations in the right proximal tibia. Hypointense signal on coronal T1-weighted images (A) and hyperintensity on fat-suppressed T2-weighted images (B) without corresponding changes of the bone structure were shown on X-ray imaging (C and D) but with focal increased uptake was shown on scintigraphy (E). Osteoarthritis was noted in the right knee and both ankles/feet.

Figure 5

H&E images of EBUS FNA biopsy. A representative H&E image (x20 magnification) from the second EBUS FNA biopsy of mediastinal LN shows multiple non-caseating granulomata (A). x40 magnification shows a single non-caseating granuloma (B). EBUS FNA, endobronchial ultrasound-guidedfine-needle aspiration; LN, lymph node.