Differential Diagnosis for Left Breast Lump
The following differential diagnosis is based on the provided ultrasound and mammography results for a 40-year-old woman presenting with a palpable abnormality and pain in the left breast.
- Single Most Likely Diagnosis
- Intradermal Sebaceous Cyst: This diagnosis is most likely due to the ultrasound findings of a 0.5 cm intradermal sebaceous cyst correlating with the palpable lump, and the absence of any suspicious mammographic findings.
- Other Likely Diagnoses
- Fibrocystic Changes: Given the patient's age and the presence of scattered areas of fibroglandular density on mammography, fibrocystic changes are a possible explanation for the palpable lump and breast pain.
- Breast Cyst: Although not specifically identified on ultrasound, a breast cyst could still be a consideration given the patient's symptoms and the presence of fibroglandular density.
- Do Not Miss Diagnoses
- Breast Cancer: Although the BI-RADS assessment is 2 (benign), it is crucial not to miss breast cancer, especially given the patient's Tyrer-Cuzick lifetime risk of 7.8%. However, the absence of suspicious findings on both mammography and ultrasound makes this less likely.
- Phyllodes Tumor: These rare tumors can present as palpable lumps and may not always have characteristic imaging findings. Although unlikely, they should be considered to avoid missing a potentially malignant diagnosis.
- Rare Diagnoses
- Lipoma: A benign tumor made of fat tissue, which could present as a palpable lump but is less common in the breast.
- Hamartoma: A benign breast tumor that could cause a palpable abnormality, although it is relatively rare.
- Pseudoangiomatous Stromal Hyperplasia (PASH): A rare benign condition that can cause a palpable lump, but it is not commonly encountered.
It's essential to discuss these findings with the patient, emphasizing the most likely diagnosis (intradermal sebaceous cyst) while also addressing the importance of continued surveillance given her risk factors and the recommendations for annual screening mammography.