Histologic sections from a rapidly enlarged cervical lymph node in a 35-year-old female reveal a diffuse, monotonous proliferation of small, noncleaved lymphocytes, which are forming a “starry sky” appearance because numerous tingible-body macrophages are present. A touch prep reveals that many of these cells have cytoplasmic vacuoles, which would most likely react with

**Core Concept**
The question describes a histological finding consistent with **Burkitt lymphoma**, a type of non-Hodgkin lymphoma characterized by a specific morphological appearance, including a "starry sky" pattern due to the presence of tingible-body macrophages. This pattern is indicative of a high proliferation rate and apoptosis within the tumor. The presence of cytoplasmic vacuoles in the lymphoma cells is a key diagnostic feature.

**Why the Correct Answer is Right**
Burkitt lymphoma cells are known to have cytoplasmic vacuoles that contain **monoclonal surface immunoglobulin**, which would react with antibodies against immunoglobulin light chains (kappa or lambda). This is a hallmark feature of Burkitt lymphoma, distinguishing it from other types of lymphoma. The vacuoles are essentially distended rough endoplasmic reticulum filled with immunoglobulin.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because while certain lymphomas may express specific antigens, the description given points more specifically towards immunoglobulin-containing vacuoles.
**Option B:** This is not directly relevant to the cytoplasmic vacuoles described in Burkitt lymphoma cells.
**Option C:** Although certain lymphomas may have specific cytokine profiles, this does not directly relate to the vacuoles' content in Burkitt lymphoma.

**Clinical Pearl / High-Yield Fact**
Burkitt lymphoma is known for its rapid growth rate and potential for widespread disease at presentation, making prompt diagnosis and treatment crucial. The "starry sky" appearance and cytoplasmic vacuoles in lymphoma cells are key diagnostic features.

**Correct Answer:** D. Immunoglobulin.

✓ Correct Answer: B. Oil red O