Differential Diagnosis

• Single most likely diagnosis
  • Cellulitis with lymphadenitis: The patient's presentation of a painful swelling in the groin, spreading redness, and fever is consistent with cellulitis, a bacterial skin infection. The presence of multiple hypoechoic masses representing abnormal lymph nodes (lymphadenitis) supports this diagnosis, as it often occurs in response to infection.
• Other Likely diagnoses
  • Lymphoma: Given the patient's history of a similar episode on the same side and the presence of abnormal lymph nodes, lymphoma is a possible diagnosis. However, the acute presentation with fever and spreading redness is less typical for lymphoma.
  • Soft tissue sarcoma: Although less common, soft tissue sarcomas can present as a painful mass with surrounding inflammation and fever. The patient's history of a similar episode and the presence of a hard, swollen mass raise this possibility.
  • Abscess or infected cyst: The patient's symptoms and the presence of a hard, swollen mass could also be consistent with an abscess or infected cyst, particularly if the stye (hordeolum) is related to the current infection.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Necrotizing fasciitis: This is a life-threatening condition characterized by necrosis of the fascia and soft tissues. Although the patient's presentation is not typical (e.g., no clear trauma, no significant abdominal pain), the spreading redness and fever warrant consideration of this diagnosis.
  • Septic thrombophlebitis: If the patient has a deep vein thrombosis (DVT) that becomes infected, it could present with fever, swelling, and redness in the affected limb. This diagnosis is critical to consider due to the high risk of sepsis and pulmonary embolism.
• Rare diagnoses
  • Kikuchi-Fujimoto disease: This is a rare, self-limiting condition characterized by lymphadenitis, fever, and rash. Although it is uncommon, it could be considered in the differential diagnosis, particularly if other tests are negative.
  • Kimura disease: This is a rare, chronic inflammatory disorder that can present with lymphadenopathy, fever, and rash. It is more common in Asian males, but it should be considered in the differential diagnosis if other tests are negative.