Squamous inclusion cyst in a sentinel axillary lymph node associated with breast malignancy

Area of Science:

• Pathology
• Surgical Oncology
• Breast Cancer Diagnosis

Background:

• Axillary intranodal squamous inclusion cysts (AISICs) are uncommon benign lesions.
• These cysts can be mistaken for metastatic carcinoma in lymph node evaluations.
• Accurate diagnosis is crucial for appropriate patient management, especially in breast cancer staging.

Observation:

• A 52-year-old female presented with a suspicious breast lump, diagnosed as infiltrating ductal carcinoma.
• Initial mammogram indicated malignancy, leading to lumpectomy and subsequent modified radical mastectomy.
• Frozen section analysis of axillary sentinel lymph nodes revealed a squamous inclusion cyst in one node.

Findings:

• Histological examination confirmed infiltrating ductal carcinoma of the breast.
• Benign histology, including a squamous inclusion cyst, was noted in the axillary sentinel lymph nodes.
• All lymph nodes examined from the mastectomy specimen were benign.

Implications:

• This case underscores the importance of recognizing rare benign mimics of malignancy in lymph node pathology.
• Awareness of AISICs can prevent misdiagnosis and unnecessary aggressive treatment in breast cancer patients.
• Accurate interpretation of sentinel lymph node biopsies is vital for precise cancer staging and treatment planning.