Breast metastases from primary lung cancer: a retrospective case series on clinical, ultrasonographic, and immunohistochemical features

Abstract

Background: Lung cancer metastases to the breast are less common and consequently have received much less attention in clinical practice. The purpose of this study was to provide a better understanding of clinical, ultrasonographic, and immunohistochemical features of breast metastases from primary lung cancer.

Methods: This retrospective case series included patients with breast metastases from primary lung cancer between January 2012 and December 2020. Clinical features, ultrasonographic characteristics, and immunohistochemical findings were evaluated in this analysis.

Results: In all, 7 cases (mean ± standard deviation age: 57.4±8.3 years; range, 49-70 years) were evaluated. The maximum size of breast lesions in 6 cases ranged from 1.2 to 4.5 cm, while 1 case showed a diffused pattern. Ultrasound features of breast metastases from lung cancer were irregular (5/7, 71.4%), indistinct (6/7, 85.7%), hypoechoic (7/7, 100.0%), and parallel (6/7, 85.7%) masses without calcification. Immunohistochemical staining test was positive for thyroid transcription factor 1 (TTF-1) in all patients (7/7, 100.0%), 3 cases (3/5, 60.0%) were negative for p63, 5 cases (5/5, 100.0%) were positive for cytokeratin 7 (CK7), 4 cases (4/5, 80.0%) were positive for napsin A.

Conclusions: The ultrasonographic features of lung metastases to the breast are clinically important to understand. A known history of the primary lung cancer is of great importance when evaluating patients with a breast nodule. The presence of an ipsilateral lung cancer, breast nodule and axillary lymphadenopathy should be considered with pathological and immunohistochemical data to differentiate breast metastases from a primary breast malignancy in this setting.

Keywords: Breast metastases; case series; immunohistochemistry; lung cancer; ultrasonography.

Figure 1

Ultrasonography for breast metastases from primary lung cancer. Patient No. 5: a 53-year-old female with adenocarcinoma of right lung. Ultrasonography shows a diffused irregular indistinct and heterogeneous hypoechoic mass in the right breast with the long axis parallel to the skin, shadowing posterior features (white arrow) (A), and ipsilateral axillary lymph adenopathy (cross symbol) (B).

Figure 2

Ultrasonography for breast metastases from primary lung cancer. Patient No. 4: a 53-year-old female with small cell lung cancer of right lung. Ultrasonography shows an oval indistinct and homogeneous hypoechoic mass in the right breast with the long axis parallel to the skin (A), and ipsilateral axillary lymph adenopathy (cross symbol) (B).

Figure 3

Ultrasonography for breast metastases from primary lung cancer. Patient No. 2: a 52-year-old female with adenocarcinoma of left lung. (A) Ultrasonography shows an irregular indistinct and heterogeneous hypoechoic mass in the left breast with the long axis parallel to the skin, enhancement posterior features (cross symbol); (B) color Doppler flowing imaging shows blood flow signals inside the mass.

Figure 4

Histological features of breast metastases from primary lung cancer. Patient No. 1: metastasis from lung adenocarcinoma (A, H&E 200×), napsin A (B, immunostain 200×) and thyroid transcription factor 1 (C, immunostain 200×); Patient No. 4: metastasis from small cell lung cancer (D, H&E 200×), synaptophysin (E, Immunostain 200×) and cluster of differentiation 56 (F, immunostain 200×). The scale bar is 100 µm for A-F.