Pleomorphic lobular carcinoma (PLC) is a less common, aggressive form of invasive lobular carcinoma (ILC), a breast cancer originating in the milk-producing glands. Unlike classic ILC, PLC exhibits distinct cellular characteristics under microscopic examination. This subtype accounts for approximately 10% of all lobular carcinomas.
Characteristics of Pleomorphic Lobular Carcinoma
PLC is characterized by specific pathological features. Histologically, PLC cells display larger, irregularly shaped nuclei with prominent nucleoli and increased mitotic activity, contrasting with the uniform, smaller cells of classic ILC.
The growth pattern of PLC often involves diffuse infiltration, with cancer cells spreading individually or in single-file lines through breast tissue rather than forming a distinct lump. This diffuse growth makes the tumor challenging to detect through conventional imaging. PLC also tends towards larger tumor size, more frequent lymph node involvement, and higher rates of distant metastasis at diagnosis compared to classic ILC.
PLC often affects postmenopausal women, though cases in younger individuals, particularly those with BRCA2 mutations, have been observed. Despite its aggressive behavior, PLC shares molecular alterations with classic ILC, such as changes in the CDH1 gene, which affect E-cadherin protein function.
Identifying and Assessing the Cancer
Identifying PLC can be challenging due to its unique growth pattern. Patients may experience subtle symptoms, such as a vaguely defined, slowly growing mass that is difficult to feel. Its diffuse infiltration often makes it hard to visualize on standard imaging.
Mammography, ultrasound, and MRI are used for detection, but PLC can be missed or underestimated in size. MRI, while more sensitive for detecting multifocal lesions, may still show non-specific enhancement patterns. Due to these imaging challenges, a definitive diagnosis relies on a biopsy, such as a core needle or excisional biopsy, for microscopic tissue examination.
Pathological examination confirms PLC and analyzes tumor characteristics, including hormone receptor status (estrogen receptor and progesterone receptor), HER2 status, and Ki-66 expression. This helps determine the tumor’s biological profile and guide treatment. Staging the cancer, which evaluates tumor size, lymph node involvement, and distant metastasis, determines the disease’s extent.
Treatment Strategies
Treatment for PLC typically involves a multidisciplinary approach, combining local and systemic therapies. Surgical intervention is a primary local treatment, which may involve a lumpectomy or a mastectomy. Sentinel lymph node biopsy or axillary dissection may assess for lymph node involvement, influencing staging and further treatment.
Radiation therapy may follow surgery, especially after a lumpectomy or if lymph nodes are involved, to reduce local recurrence risk. Systemic treatments target cancer cells throughout the body. Chemotherapy is often considered for higher-grade tumors or those with lymph node involvement.
Hormone therapy, such as tamoxifen, raloxifene, anastrozole, or exemestane, is an option if the tumor is hormone receptor-positive, as these medications block estrogen. Targeted therapies, such as HER2-directed agents like neratinib, are used if the tumor tests positive for HER2. Immunotherapy may also be considered in certain situations based on specific tumor characteristics.
Outlook and Ongoing Care
The outlook for individuals with PLC is generally more aggressive than for classic invasive lobular carcinoma, due to its tendency for larger tumor size, higher histological grade, and more advanced stage at diagnosis. However, individual outcomes vary significantly based on cancer stage, biological characteristics, and treatment response.
Following initial treatment, ongoing care is a long-term commitment. Regular follow-up appointments include physical examinations and imaging tests like mammograms or MRIs to monitor for recurrence. These surveillance efforts aid early detection.
Survivorship care also focuses on managing potential long-term treatment side effects, such as lymphedema or fatigue, and promoting overall well-being. This approach helps individuals maintain health and quality of life after active treatment.