Russel bodies are seen in?
**Core Concept**
Russell bodies are characteristic pathological features seen in certain types of cells, particularly plasma cells, under the microscope. They are formed due to the accumulation of immunoglobulin light chains within the endoplasmic reticulum, leading to the formation of large, eosinophilic inclusions. This process is often associated with conditions like multiple myeloma and Waldenström macroglobulinemia.
**Why the Correct Answer is Right**
The formation of Russell bodies is a result of the abnormal accumulation of immunoglobulin light chains, which are essential components of antibodies. In conditions like multiple myeloma, there is an overproduction of immunoglobulins, leading to the accumulation of light chains within the endoplasmic reticulum. This accumulation causes the formation of Russell bodies, which are seen as large, eosinophilic inclusions within the cytoplasm of plasma cells. The presence of Russell bodies is a diagnostic feature of these conditions.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Russell bodies are not typically associated with lymphoblasts, which are immature cells involved in the development of lymphoid tissues.
**Option B:** This option is incorrect because Russell bodies are not a characteristic feature of epithelial cells, which are a type of cell found in various tissues, including the skin, gut, and respiratory tract.
**Option C:** This option is incorrect because Russell bodies are not a hallmark of histiocytes, which are cells involved in the immune response and are often found in tissues like the spleen and lymph nodes.
**Clinical Pearl / High-Yield Fact**
Russell bodies are a classic example of a pathological feature that can be seen in certain types of plasma cell dyscrasias. They are often associated with conditions like multiple myeloma, which can lead to the accumulation of immunoglobulin light chains in the endoplasmic reticulum, causing the formation of these characteristic inclusions.
**Correct Answer:** D.