Diffuse skin thickening of the breast as a rare form of presentation of lung cancer metastasis

Clinical History

The patient is a 55-year-old woman, with hypertension and dyslipidaemia, who smokes between 15 and 20 cigarettes a day, and underwent a myomectomy 20 years ago.

She sought medical attention for cervical pain and asthenia that had gradually developed over a 6-month period.

Imaging Findings

She was initially given a spine X-ray, which revealed a fracture of C4 (Fig. 1) that was probably pathological.

The CT scan confirmed the destructive injury in the vertebral body of C4 (Fig. 2a), with extension to the left pedicle. Probably lytic lesions were found in the underlying vertebral bodies, and blastic lesions in the right iliac bone (Fig. 2b) and vertebral body of L3.

A spiculated mass was also identified in the upper lobe of the right lung (Fig. 3a).

A diffuse skin thickening of the left breast was also observed (Fig. 3b, 4a, 4b and 4c), together with multiple ipsilateral axillary adenopathies. We did not identify any focal masses in the breast, or any other alterations.

US-guided biopsy of the left breast skin was performed and the lesions were proved to be breast metastases from a pulmonary adenocarcinoma.

Discussion

Metastases to the breast from an extra-mammary tumour are quite rare. Depending on the series, they vary between 0.2% and 1.3% (with an incidence of up to 6 – 7% in autopsies), and when they do present, they indicate that the disease is widespread. They are much more frequent in women, in a ratio of 5-6 to 1 [1, 2, 4, 5]. No clear predisposing factors have been identified in the cases studied.

They normally present in the subcutaneous fat, unlike primary breast tumours, which normally originate in the mammary glandular tissue. Mammary metastases of lung cancer include a similar histology to the primary lesion, with infiltrative proliferation of the tumour cells surrounding the duct and lobe of the mammary gland, and usually preserve the characteristics of the mammary gland structure.

From a clinical perspective, they are indistinguishable from a primary breast tumour [2, 4, 5]. Patients usually note a palpable mass or masses, frequently in the upper-outer quadrant of the breast. Multiple, bilateral, and diffuse involvement are also quite rare, as well as the involvement of the axillary lymphatic ganglia. They do not usually cause retraction of the skin or of the nipple.

The tumours that most usually metastasise to the breast are contralateral breast cancer, haematological diseases (lymphoma and leukaemia), and disseminated melanoma. Other less frequent primary tumours are cancers of the lung, ovary, prostate, and stomach [1, 3].

According to the literature reviewed, we have seen the lung tumour that most frequently metastasise in the breast is the small cell carcinoma. There are about 30 NSCLC cases reports, of which 12 were adenocarcinomas [6, 7].

From a radiological perspective, metastases in the breast can be seen as single or multiple masses, or as a diffuse skin thickening. They are indistinguishable from the primary breast tumour. They usually appear as masses with more or less clearly defined outlines, and are normally not spiculated. Microcalcifications are rare, although they may appear in the metastases of certain primary tumours, such as ovarian cancer [4].

In the ultrasound scan, the metastases appeared as hypoechoic masses with defined margins, and occasionally with posterior acoustic enhancement. The colour Doppler study revealed an increased vascularisation [2].

Metastases to the breast or armpit have a poor prognosis, with a more than 80% 1-year mortality rate. For this reason, correct diagnosis is essential in order to avoid inadequate and unnecessary procedures and treatments.

Differential Diagnosis List

Final Diagnosis

Breast metastasis from a pulmonary adenocarcinoma

URL:	https://www.eurorad.org/case/14895
DOI:	10.1594/EURORAD/CASE.14895
ISSN:	1563-4086