DIFFICULTIES OF DAIGNOSING LOBULAR CARCINOMA

A sixty-five year old lady was referred to the Clinic by her gynaecologist with a lump in her right breast. She had been aware of a thickening in the breast for between three and six months. Six months prior to presentation, she had a screening mammogram which was reported as normal. Three months later, the patient presented to her GP with a thickening in her right breast. Mammogram and ultrasound were performed at that time and reported as normal. Biopsy was not performed.

On presentation to the Clinic a further three months later there was a tender thickening in the right upper outer quadrant with associated nipple retraction. There was no lymphadenopathy.

The outside mammograms were reviewed and further work-up views performed. These revealed a suspicious architectural distortion in the right upper outer quadrant. There was a ‘tent sign’ on the right CC view, indicative of a mass pulling the breast parenchyma into it. In addition, the right breast could be seen to be ‘shrinking’ over time. A right breast ultrasound confirmed the presence of a 2cm malignant mass in the upper outer quadrant.

Fine Needle Aspiration Biopsy (FNAB) of the mass was performed and reported as atypical. Core Biopsy of the lesion revealed an infiltrating lobular carcinoma. Typical of invasive lobular carcinoma, the cells were infiltrating the breast structures in single files and cords, and were surrounded by a fibrous stromal reaction^[1].

The patient went on to have a wide local excision of the tumour along with sentinel node biopsy. The histopathology showed a 40mm Grade 1 invasive lobular carcinoma. No lymph nodes were involved.

This case demonstrates some of the difficulties of diagnosing lobular carcinoma, which comprises approximately 8-14% of all breast cancers^[2]. Invasive lobular carcinoma is characterised by small, round cells that have only mildly pleomorphic nuclei and are thus difficult to identify on FNAB. They classically infiltrate the stroma in single (“Indian”) file and surround benign breast structures^[1]. Infiltration typically does not destroy anatomic structures and is associated with sclerosis, reducing the cell yield at FNAB. A pathological diagnosis of lobular carcinoma frequently requires a core biopsy.

Because the cells invade the normal architecture, lobular carcinomas often fail to form distinct masses and are not obvious on imaging. The clinical findings are often overlooked because a discrete mass is often not palpated, although thickening may be present. Occasionally they present with only focal tenderness.

The mammographic appearance in invasive lobular carcinoma may be benign or may show only subtle parenchymal asymmetry, architectural distortion or non-specific diffuse changes such as decreased breast size (‘shrinking breast’) accompanied by a diffuse increase in density. Occasionally lobular carcinoma presents with a relatively well-circumscribed mass, which may appear benign on mammogram^[3]. Sonographically, a hypoechoic ill-defined mass with significant shadowing is the usual finding.

Once again, this case demonstrates the importance of correlating clinical and imaging findings, and of performing a biopsy on any asymmetrical clinical thickening in the breast of a postmenopausal woman who is not on hormone therapy. The Triple Test, upon which breast cancer diagnosis is based, comprises:

1. Medical history and clinical breast examination,
2. Imaging: mammography and /or ultrasound, and
3. Biopsy: FNAB and/or Core biopsy

Dr Lauren Arnold
Breast Physician

References:

1. Arpino G , Bardou VJ , Clark GM et al, Infiltrating lobular carcinoma of the breast: tumor characteristics and clinical outcome. Breast Cancer Res 2004, 6:R149-R156
2. Harake MD, Maxwell AJ, Sukumar SA . Primary and metastatic lobular carcinoma of the breast. Clin Radiol 2001 Aug:56(8):621-30.
3. Krecke KN, Gisvold JJ. Invasive lobular carcinoma of the breast: mammographic findings and extent of disease at diagnosis in 184 patients. AJR Am J Roentgenol. 1993 Nov;161(5):957-60.