Differential Diagnosis for Unilateral Underarm Mass
Single Most Likely Diagnosis
- Breast Cancer Metastasis: A 38-year-old female presenting with a unilateral underarm mass and clusters of lymph nodes on ultrasound is highly suggestive of breast cancer metastasis, especially given the proximity of the lymph nodes to the breast tissue. Workup should include:
- Mammography or breast MRI to evaluate for a primary breast tumor
- Biopsy of the lymph node to confirm metastasis
- Further staging workup if breast cancer is confirmed
Other Likely Diagnoses
- Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with lymphadenopathy in the axilla. Workup should include:
- Biopsy of the lymph node to confirm lymphoma
- Imaging studies such as CT or PET scans to evaluate for systemic involvement
- Laboratory tests to evaluate for bone marrow involvement
- Infectious or Inflammatory Conditions: Conditions such as cat-scratch disease, tuberculosis, or sarcoidosis can cause lymphadenopathy. Workup should include:
- Laboratory tests to evaluate for infectious causes (e.g. blood cultures, serologies)
- Imaging studies to evaluate for systemic involvement
- Biopsy of the lymph node to confirm diagnosis
- Soft Tissue Tumor: A soft tissue tumor such as a lipoma or sarcoma can present as a mass in the axilla. Workup should include:
- Imaging studies such as MRI or CT scans to evaluate the extent of the tumor
- Biopsy of the tumor to confirm diagnosis
Do Not Miss Diagnoses
- Melanoma Metastasis: Melanoma can metastasize to the axillary lymph nodes, and a delay in diagnosis can be deadly. Workup should include:
- Examination of the skin to evaluate for a primary melanoma
- Biopsy of the lymph node to confirm metastasis
- Further staging workup if melanoma is confirmed
- Leukemia: Leukemia can cause lymphadenopathy, and a delay in diagnosis can be life-threatening. Workup should include:
- Laboratory tests to evaluate for leukemia (e.g. blood counts, bone marrow biopsy)
- Imaging studies to evaluate for systemic involvement
Rare Diagnoses
- Castleman Disease: A rare condition that can cause lymphadenopathy, often in the axilla. Workup should include:
- Biopsy of the lymph node to confirm diagnosis
- Laboratory tests to evaluate for systemic involvement
- Imaging studies to evaluate for extent of disease
- Kimura Disease: A rare condition that can cause lymphadenopathy and eosinophilia. Workup should include:
- Biopsy of the lymph node to confirm diagnosis
- Laboratory tests to evaluate for eosinophilia and systemic involvement
- Imaging studies to evaluate for extent of disease