Differential Diagnosis
- Single most likely diagnosis
- Cellulitis: The patient presents with a swollen area next to his left ear, which started as a bug bite and has been increasing in swelling over the past 2 days. The absence of fever, chills, and other systemic symptoms, along with the localized swelling, makes cellulitis a likely diagnosis. The mild peri-orbital edema seen on the CT maxillofacial scan also supports this diagnosis.
- Other Likely diagnoses
- Insect bite reaction: The patient's symptoms started with a bug bite, and the swelling could be an allergic reaction to the bite. The scratchy throat could be a systemic allergic reaction.
- Contact dermatitis: The patient may have come into contact with an allergen or irritant that caused a skin reaction, leading to the swelling and scratchy throat.
- Angioedema: Although less likely, the patient's symptoms could be indicative of angioedema, especially given the peri-orbital edema and scratchy throat.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Orbital cellulitis: Although the CT scan did not show evidence of an abscess, orbital cellulitis is a serious condition that can lead to vision loss and other complications if not treated promptly.
- Necrotizing fasciitis: This is a rare but life-threatening condition that can occur if the infection spreads to the fascia. The patient's lack of systemic symptoms makes this less likely, but it should still be considered.
- Lyme disease: If the bug bite was from a tick, the patient could be at risk for Lyme disease, which can have serious complications if not treated promptly.
- Rare diagnoses
- Erythema migrans: This is a rash that can occur in the early stages of Lyme disease, although it is typically seen as a distinctive "bull's-eye" rash.
- Brown recluse spider bite: This type of spider bite can cause necrotic lesions and other systemic symptoms, although it is relatively rare.
SOAP Note
Subjective
The patient is a 47-year-old male who presents to the ED complaining of a bug bite next to his left ear that has become increasingly swollen over the past 2 days. He denies fever, chills, shortness of breath, and fatigue. He reports developing a scratchy throat since this morning.
Objective
- Vital signs: Not provided
- Physical exam: Swelling next to the left ear, mild peri-orbital edema
- Labs: CBC shows monocytes absolutely 1.1, otherwise unremarkable. CMP shows ALT-SGPT 59, otherwise unremarkable.
- Imaging: CT maxillofacial shows mild peri-orbital edema, possible representing inflammatory process. No evidence of abscess. The sinuses are well-aerated. No evidence of fracture.
Assessment
The patient's symptoms are most consistent with cellulitis, although other diagnoses such as insect bite reaction, contact dermatitis, and angioedema should be considered.
Plan
- Treat the patient with antibiotics for cellulitis, such as cephalexin or dicloxacillin.
- Provide pain management as needed.
- Monitor the patient's symptoms and adjust the treatment plan as necessary.
- Consider further testing, such as a Lyme disease test, if the patient's symptoms do not improve with treatment.