Invasive lobular carcinoma

A type of breast cancer that begins in the lobules of the breast

Invasive lobular carcinoma (ILC) is a type of breast cancer that begins in the lobules of the breast, which are the glands that produce milk. It is the second most common type of breast cancer after invasive ductal carcinoma.

Pathophysiology

Invasive lobular carcinoma originates in the lobules, which are the milk-producing glands of the breast. Unlike ductal carcinoma, which begins in the milk ducts, ILC tends to spread in a more diffuse pattern, often making it more challenging to detect on mammography. The cancer cells invade the surrounding breast tissue and can metastasize to other parts of the body.

Clinical Presentation

Patients with invasive lobular carcinoma may present with a variety of symptoms. Commonly, there is a thickening or hardening of the breast tissue rather than a distinct lump. Other symptoms can include changes in breast size or shape, skin dimpling, or nipple inversion. Due to its diffuse growth pattern, ILC may not form a palpable mass, making clinical detection more difficult.

Diagnosis

The diagnosis of invasive lobular carcinoma typically involves a combination of imaging studies and biopsy. Mammography and ultrasound are commonly used, but due to the diffuse nature of ILC, magnetic resonance imaging (MRI) may be more effective in some cases. A definitive diagnosis is made through a biopsy, where a sample of breast tissue is examined under a microscope to identify cancerous cells.

Histological Features

Under the microscope, invasive lobular carcinoma is characterized by small, non-cohesive cells that invade the stroma in a single-file pattern. This is due to the loss of E-cadherin, a protein that helps cells stick together. The lack of E-cadherin is a hallmark of ILC and helps differentiate it from other types of breast cancer.

Treatment

The treatment of invasive lobular carcinoma typically involves a combination of surgery, radiation therapy, and systemic therapies such as chemotherapy, hormone therapy, and targeted therapy. The choice of treatment depends on the stage of the cancer, hormone receptor status, and other factors.

Surgical Options

Surgical treatment may include lumpectomy or mastectomy, depending on the size and location of the tumor and patient preference. Sentinel lymph node biopsy or axillary lymph node dissection may be performed to assess the spread of cancer to the lymph nodes.

Systemic Therapies

Hormone therapy is often used in cases where the cancer is hormone receptor-positive. Common medications include tamoxifen and aromatase inhibitors. Chemotherapy may be recommended for more advanced stages or aggressive forms of ILC. Targeted therapies, such as HER2 inhibitors, are used if the cancer overexpresses the HER2 protein.

Prognosis

The prognosis for patients with invasive lobular carcinoma varies depending on the stage at diagnosis and other factors such as hormone receptor status. Generally, ILC has a similar prognosis to invasive ductal carcinoma when matched for stage and other prognostic factors. However, due to its tendency to be diagnosed at a later stage, careful monitoring and follow-up are essential.

Related pages

• Breast cancer
• Invasive ductal carcinoma
• Mammography
• Hormone therapy (oncology)