Invasive Lobular Carcinoma

Invasive lobular carcinoma (ILC) is the second most common type of invasive breast cancer, accounting for approximately 10-15% of all invasive breast cancer diagnoses and is more likely to be diagnosed in both breasts compared to other types of breast cancer.

Fundamentals Of Invasive Lobular Carcinoma

Invasive lobular carcinoma is a type of breast cancer which begins to grow in lobules. Lobules are also known as milk producing glands on the breast. Furthermore as it is a type of invasive breast cancer, that means the cancer has spread beyond the lobules into surrounding breast tissue. This type of breast cancer grows in a unique way, often spreading in a single line through the tissue, which makes the detection more challenging as compared to other forms of breast cancer, such as invasive ductal carcinoma.

Types of Invasive Lobular Carcinoma

Classic Invasive Lobular Carcinoma

Classic Invasive Lobular Carcinoma (ILC) is named classic due to its differentiative histological features which includes discohesive growth pattern which means that the cells are not sticking together well or does not work together smoothly and are characterized by small, non-cohesive cells (does not form strong connection with one another) that take over surrounding tissues in single line rather than in groups.

Some key insights about Classic Invasive Lobular Carcinoma
  • This cancer accounts for 10-15% of all invasive breast cancer diagnoses. 
  • This type of cancer typically occurs in older women, with about two-thirds of cases diagnosed in those aged 55 or older.
  • Most classic ILC tumors are hormone receptor-positive and HER2-negative, which often leads to a favorable response to hormone therapies. Despite these positive characteristics, the subtlety of its growth can result in late diagnoses

Pleomorphic lobular carcinoma

Pleomorphic lobular carcinoma (PLC) is a distinct variant of invasive lobular carcinoma (ILC) characterized by marked cellular atypia and nuclear pleomorphism. Unlike classic ILC, which features small, non-cohesive cells that invade surrounding tissues in a linear pattern, PLC presents with enlarged nuclei and a higher mitotic rate. This variant retains the discohesive growth pattern typical of lobular carcinomas but exhibits greater variability in cell size and shape, often including signet ring cells and eosinophilic cytoplasm.

Some key insights about Pleomorphic lobular carcinoma
  • PLC is characterized by higher nuclear pleomorphism and a greater degree of cellular atypia compared to classic invasive lobular carcinoma, leading to a more aggressive clinical course and poorer prognosis.
  • Characterized by higher nuclear pleomorphism and cellular atypia, leading to a poorer prognosis compared to classic ILC.
  • Microscopic evaluations show cancer cells often surrounded by mucus, with enlarged, irregular nuclei.
  • Frequently exhibits ERBB2 amplification and TP53 mutations, contributing to its aggressive behavior

Solid Invasive Lobular Carcinoma (ILC)

Solid Invasive Lobular Carcinoma (ILC) is a variant characterized by solid clusters of cancer cells rather than the typical single-file arrangement seen in classic ILC. This type features larger, more varied cells and shows higher mitotic activity, indicating a more aggressive behavior. Unlike classic ILC, solid ILC can appear as homogeneous masses, making it harder to identify

Some key insights about Solid Invasive Lobular Carcinoma (ILC)
  • Solid ILC tends to exhibit higher mitotic activity and cellular pleomorphism, which are associated with a more aggressive clinical course compared to classic ILC.
  • Patients with solid ILC generally face a worse prognosis than those with classic ILC due to its aggressive nature and higher likelihood of metastasis.
  • Solid ILC can be more easily detected than classic ILC, it still poses challenges in imaging and may require advanced techniques, such as MRI or contrast-enhanced spectral mammography, for accurate assessment.

Tubulolobular carcinoma

Tubulolobular carcinoma is a variant of invasive lobular carcinoma (ILC) that combines features of both classic ILC and tubular carcinoma. This subtype is characterized by a distinct growth pattern where small, uniform cells form tubules, occupying less than 90% of the lesion area while still exhibiting the discohesive growth typical of lobular carcinoma. The cells in tubulolobular carcinoma do not adhere tightly to one another, leading to a lack of cohesion, which allows them to invade surrounding tissues in a manner similar to classic ILC.

Some key insights about Mucinous ductal carcinoma
  • Tubulolobular carcinoma accounts for 1-2% of all invasive breast carcinomas.
  • This type exhibits a mix of small tubules and lobular-like cells, combining features of both tubular and lobular carcinomas, with small round tubules and single-file infiltration.
  • It tends to be more aggressive than pure tubular carcinoma, with approximately 16% of patients showing lymph node metastases.
  • The mean age at diagnosis is typically between 59 and 60 years, although it can occur in a wider range from 43 to 79 years.

Alveolar Invasive Lobular Carcinoma (ILC)

The alveolar variant of invasive lobular carcinoma (ILC) is a less common subtype characterized by aggregates of cancer cells arranged in clusters or “alveoli,” typically comprising at least 20 cells. This variant retains the hallmark features of classic ILC, such as a lack of cellular cohesion and infiltrative growth patterns, but can also mimic lobular carcinoma in situ (LCIS). It is often identified as a minor component within classic ILC but can occasionally present in a pure form. While its prognostic significance remains uncertain, some studies suggest that the alveolar variant may have a better prognosis compared to other ILC subtypes. The diagnosis can be challenging due to its subtle infiltrative nature, and it often requires advanced imaging techniques for detection

Some key insights about Alveolar Invasive Lobular Carcinoma (ILC)
  • It is often identified as a minor component within classic ILC but can also present as a pure form. This variant may represent a transitional stage between lobular carcinoma in situ (LCIS) and classic ILC.
  •  The alveolar variant typically shows strong expression of estrogen receptors (ER), which is consistent with the overall hormonal sensitivity of ILC.
  • Its subtle infiltrative nature can complicate diagnosis, often requiring advanced imaging techniques for accurate detection.

“Invasive Lobular Carcinoma: Insights and Care”

Group of people who can get affected by invasive lobular carcinoma
  1.  ILC predominantly affects women, but it can also occur in men, although the incidence is significantly lower. It is most commonly diagnosed in women aged 55 to 65.
  2. Individuals with a family history of breast cancer, particularly those with mutations in the BRCA1 or BRCA2 genes, are at an increased risk.
    but it is more commonly diagnosed in people over the age of 55.

Stages of invasive lobular carcinoma

 Following are the  five stages of invasive lobular carcinoma:

  • Stage 0: Also known as lobular carcinoma in situ (LCIS), this stage indicates that cancer cells are confined to the lobules and have not invaded surrounding breast tissue.
  • Stage 1:
    1. Stage IA: The tumor is small (≤ 2 cm) and has not spread to any lymph nodes.
    2. Stage IB: The cancer may have spread to 1-3 nearby lymph nodes but is still ≤ 2 cm in size.
  • Stage 2:
    1. Stage IIA: The tumor is between 2 cm and 5 cm and may have spread to 1-3 nearby lymph nodes.
    2. Stage IIB: The tumor is larger than 5 cm but has not spread to any lymph nodes.
  • Stage 3: 
    1. Stage IIIA: The tumor can be any size and has spread to 4-9 axillary (armpit) lymph nodes or internal mammary lymph nodes without distant metastasis.
    2. Stage IIIB: Tumors in this stage may have caused swelling in the breast or have spread to the chest wall, with involvement of up to 9 nearby lymph nodes.
    3. Stage IIIC: The tumor can be any size and has spread to 10 or more axillary lymph nodes, internal mammary lymph nodes, or nodes under the collarbone, but has not metastasized to distant sites.

Stage 4: This stage indicates that the cancer has metastasized to other organs, which may include the bones, liver, lungs, brain, or distant lymph nodes.

Symptoms of invasive lobular carcinoma

Here are some signs of invasive lobular carcinoma that people might experience :-

  • A palpable mass or thickening in the breast.
  • Changes in breast shape or size.
  • Nipple discharge or retraction.
  • Swelling or changes in skin texture over the breast.

Diagnosis for invasive lobular carcinoma

Clinical Examination: Physical assessment by a healthcare provider.
Imaging Studies: Mammograms, ultrasounds, and MRIs to visualize abnormalities.
Biopsy: Definitive diagnosis through tissue sampling to check for cancer cells.

Treatment for invasive lobular carcinoma
  • Surgery: Lumpectomy or mastectomy to remove the tumor.
  • Radiation Therapy: Often used post-surgery to eliminate remaining cancer cells.
  • Hormone Therapy: For hormone receptor-positive tumors, medications may be prescribed to block hormones that fuel cancer growth.
  • Chemotherapy: May be used depending on the stage and characteristics of the tumor.

Side effects of invasive lobular carcinoma treatment
  1. Fatigue and weakness from chemotherapy and radiation therapy.
  2. Nausea and vomiting associated with chemotherapy.
  3. Hormonal changes leading to hot flashes, mood swings, or weight gain from hormone therapy.
  4. Surgical side effects such as pain, swelling, and changes in breast appearance.
References for the article