Differential Diagnosis

The patient's presentation is complex, with a history of cancer, a new lump on the chest wall, and an abnormal Quantiferon-TB test result that is not indicative of a M. tuberculosis complex infection. Given these details, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • Sarcoidosis: This condition is characterized by the growth of granulomas (inflammatory cells) in various parts of the body, most commonly the lungs and lymph nodes. The patient's previous cancer history and the presence of a new, painless lump on the chest wall, which could be a lymph node enlargement, along with the non-specific but abnormal Quantiferon-TB test result, make sarcoidosis a plausible diagnosis. Sarcoidosis can sometimes be associated with an elevated Quantiferon-TB test due to cross-reactivity, although this is not a specific indicator.

• Other Likely Diagnoses

  • Metastatic disease from the previous cancer: Given the patient's history of dysgerminoma (a type of ovarian cancer), the new lump could potentially be a metastasis, especially since it's located near the clavicle, a common site for metastatic deposits from various primary cancers.
  • Lymphoma: This is another possibility, given the lymph node enlargement and the patient's history of cancer. Lymphomas can present with lymph node swellings in the neck or chest area.
  • Reactive lymphadenopathy: This could be a reaction to the previous cancer or its treatment, or even to an unrelated infection or inflammatory process.

• Do Not Miss Diagnoses

  • Tuberculosis (TB): Although the M. tuberculosis complex infection is considered unlikely, TB can present in various forms and can affect the lymph nodes. It's crucial not to miss this diagnosis due to its public health implications and the need for specific treatment.
  • Other infections (e.g., fungal infections): In immunocompromised patients or those with a history of cancer, opportunistic infections can occur and may present with lymphadenopathy.

• Rare Diagnoses

  • Other granulomatous diseases (e.g., histoplasmosis, coccidioidomycosis): These are less common and typically depend on geographic exposure but could present with similar symptoms.
  • Castleman disease: A rare disorder that involves an overgrowth of cells in the body's lymph nodes, which could present with lymphadenopathy.
  • Kimura disease: A rare, chronic inflammatory disorder that typically affects the head and neck region and is characterized by the presence of lymphoid follicles and eosinophilia.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and further diagnostic testing to determine the most appropriate diagnosis and treatment plan.