Differential Diagnosis for Submental Pain and Swelling in a Diabetic Patient

Single Most Likely Diagnosis

• Dental Abscess or Infection: Given the patient's complaint of right lower molar pain and the presence of diabetes, which can impair healing and increase the risk of infections, a dental abscess or infection is a highly plausible cause for the submental pain and swelling. The absence of systemic symptoms like fever and the normal WBC count do not rule out a localized infection, especially in a diabetic patient who may have altered symptom presentation.

Other Likely Diagnoses

• Submandibular Sialadenitis: This condition involves inflammation of the submandibular gland and can present with pain and swelling in the submental area. While it's less directly linked to the molar pain, it remains a consideration, especially if the dental evaluation does not reveal an obvious source of infection.
• Ludwig's Angina: Although this is a more severe condition that typically presents with significant swelling, pain, and potentially life-threatening airway compromise, its consideration is warranted given the patient's symptoms and the potential for rapid progression, especially in diabetic patients.

Do Not Miss Diagnoses

• Deep Neck Infection: Despite the CT soft tissue being negative for any acute process, deep neck infections can be subtle in their presentation and have a high potential for morbidity and mortality if not promptly treated. The absence of fever and a normal WBC count does not exclude this diagnosis, especially in diabetic patients who may have blunted inflammatory responses.
• Lemierre's Syndrome: This condition, characterized by a bacterial infection of the jugular vein, can present with neck pain and swelling. Although less common, it is a critical diagnosis to consider due to its potential severity and the need for prompt antibiotic treatment.

Rare Diagnoses

• Submental Mycobacterial Infection: Infections with mycobacteria, including tuberculosis, can present in unusual ways, including as a submental mass or swelling. This would be an uncommon diagnosis but should be considered, especially if the patient has risk factors for mycobacterial infections or if other diagnoses are ruled out.
• Salivary Gland Tumor: Although tumors of the salivary glands are rare and typically present with a more gradual onset of symptoms, they could be considered in the differential diagnosis if other causes are excluded and the swelling persists or grows over time.