What is the diagnosis for a patient presenting with a 2-month history of feeling fullness in the armpit, with imaging findings of a benign-appearing axillary lymph node (lymphadenopathy) and no evidence of fracture, dislocation, or soft tissue lesions?

Differential Diagnosis for Axillary Fullness

• Single most likely diagnosis
  • Benign axillary lymph node: The sonographic findings of a thin uniform cortex and prominent fatty hilum are characteristic of a benign lymph node, and the size of 2.9 x 2.5 x 0.9 cm is within normal limits. The patient's symptoms of fullness in the armpit for 2 months could be due to the presence of this benign lymph node.
• Other Likely diagnoses
  • Lipoma: A benign fatty tumor that could cause fullness in the armpit. Although no discrete soft tissue mass was identified, a lipoma could be isoechoic with surrounding fat and difficult to detect.
  • Cystic hygroma: A benign cystic lesion that could cause fullness in the armpit. Although no cystic lesion was identified, a small cystic hygroma could be missed on ultrasound.
  • Brachial cleft cyst: A benign cystic lesion that could cause fullness in the armpit. Although no cystic lesion was identified, a small brachial cleft cyst could be missed on ultrasound.
• Do Not Miss diagnoses
  • Lymphoma: A malignant condition that could cause lymphadenopathy and fullness in the armpit. Although the lymph node appears benign on ultrasound, lymphoma could be present and would require further evaluation with biopsy or additional imaging.
  • Metastatic disease: A malignant condition that could cause lymphadenopathy and fullness in the armpit. Although the lymph node appears benign on ultrasound, metastatic disease could be present and would require further evaluation with biopsy or additional imaging.
  • Sarcoma: A malignant condition that could cause a soft tissue mass and fullness in the armpit. Although no discrete soft tissue mass was identified, a small sarcoma could be missed on ultrasound.
• Rare diagnoses
  • Kimura disease: A rare benign condition that causes lymphadenopathy and fullness in the armpit. Although the lymph node appears benign on ultrasound, Kimura disease could be present and would require further evaluation with biopsy or additional imaging.
  • Castleman disease: A rare benign condition that causes lymphadenopathy and fullness in the armpit. Although the lymph node appears benign on ultrasound, Castleman disease could be present and would require further evaluation with biopsy or additional imaging.
  • Neurofibroma: A rare benign condition that causes a soft tissue mass and fullness in the armpit. Although no discrete soft tissue mass was identified, a small neurofibroma could be missed on ultrasound.