Differential Diagnosis for Neck Lump

The patient presents with a 7-week history of a neck lump, which has been increasing in size, and is associated with soreness, hotness, and pain that worsens with standing and improves with lying down. The lump is located in the left posterior triangle, is 2.5cm in size, soft, and has an irregular surface. It is mobile and non-tender on palpation. Given these characteristics and the patient's overall presentation, the differential diagnoses can be categorized as follows:

• Single Most Likely Diagnosis

  • Metastatic Squamous Cell Carcinoma: This is considered the most likely diagnosis due to the lump's characteristics (size, location, duration, and mobility), the patient's age, and the presence of associated symptoms such as soreness and hotness. The absence of a primary tumor does not rule out metastatic disease, as some primary sites may not be readily apparent or may have regressed.

• Other Likely Diagnes

  • Reactive Lymphadenopathy: Given the slightly elevated CRP and the presence of otitis externa, reactive lymphadenopathy due to infection or inflammation is a plausible diagnosis. However, the duration and characteristics of the lump make this less likely.
  • Tuberculous Lymphadenitis: Although less common, tuberculous lymphadenitis could present with similar symptoms, especially if the patient has been exposed to tuberculosis. The absence of systemic symptoms like fever, night sweats, and weight loss makes this less likely but does not rule it out entirely.
  • Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with lymphadenopathy. The patient's lack of systemic symptoms (fever, night sweats, weight loss) and the specific characteristics of the lump make this less likely but still a consideration.

• Do Not Miss Diagnoses

  • Thyroid Cancer with Lymph Node Metastasis: Although the lump is not in the typical location for a thyroid mass, thyroid cancer can metastasize to lymph nodes in the neck. Missing this diagnosis could have significant implications for treatment and prognosis.
  • Salivary Gland Tumors: Tumors of the salivary glands, including the parotid gland, can present as a neck lump. These can be benign or malignant, and missing a malignant tumor could impact treatment outcomes.
  • Pharyngeal or Esophageal Cancer: Cancers of the pharynx or esophagus can present with neck lymphadenopathy. These diagnoses are critical not to miss due to their significant impact on prognosis and treatment.

• Rare Diagnoses

  • Castleman Disease: A rare disorder that involves an overgrowth of cells in the lymphatic system, which can present with lymphadenopathy.
  • Kimura Disease: A rare, chronic inflammatory disorder that can cause lymphadenopathy and eosinophilia, more commonly seen in Asian males.
  • Kikuchi-Fujimoto Disease: A rare, self-limiting condition that can cause lymphadenopathy, typically in young women, and is often associated with systemic symptoms like fever.

Each of these diagnoses requires careful consideration based on the patient's presentation, history, and the results of further diagnostic tests, including imaging and potentially a biopsy. The patient's symptoms and the characteristics of the neck lump warrant a thorough investigation to determine the underlying cause.