A ‘string of pearls’ appearance is seen in –
**Core Concept**
The 'string of pearls' appearance is a radiological term used to describe a specific pattern of lymph node enlargement. This pattern is characteristic of certain conditions and is essential to recognize in diagnosing and managing patients.
**Why the Correct Answer is Right**
The 'string of pearls' appearance is typically seen in tuberculosis (TB) lymphadenitis. This condition results from the body's immune response to Mycobacterium tuberculosis infection. The lymph nodes become enlarged and form a chain-like pattern, resembling a string of pearls. This is due to the confluence of caseating granulomas within the lymph node, which leads to the characteristic radiological appearance.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the 'string of pearls' appearance is not characteristic of lymphoma. Lymphoma can cause lymph node enlargement, but it typically presents as a uniform or heterogeneous mass, rather than a string-like pattern.
* **Option B:** This option is incorrect because Kikuchi's disease is a form of histiocytic necrotizing lymphadenitis, but it does not typically present with a 'string of pearls' appearance. Kikuchi's disease is more commonly associated with a 'honeycomb' or 'popcorn' appearance on imaging.
* **Option C:** This option is incorrect because sarcoidosis is a systemic granulomatous disease that can affect the lymph nodes. However, it typically presents with a more uniform or 'honeycomb' pattern of lymph node enlargement, rather than a 'string of pearls' appearance.
**Clinical Pearl / High-Yield Fact**
When evaluating lymphadenopathy, it's essential to consider the patient's clinical presentation, laboratory results, and imaging findings in conjunction with the radiological pattern. A 'string of pearls' appearance on imaging is highly suggestive of TB lymphadenitis, and further investigation should be pursued to confirm the diagnosis.
**Correct Answer: D. Tuberculosis**