**Question:** Which subtype of Hodgkin lymphoma is negative for CD15 and CD30 markers:

A. Lymphocyte-rich Hodgkin lymphoma
B. Lymphocyte-depleted Hodgkin lymphoma
C. Mixed cellularity Hodgkin lymphoma
D. Nodular sclerosis Hodgkin lymphoma

**Correct Answer:** **B. Lymphocyte-depleted Hodgkin lymphoma**

**Core Concept:**
Hodgkin lymphoma (HL) is a type of non-Hodgkin lymphoma characterized by the presence of unique Reed-Sternberg (RS) cells, which are large, abnormal lymphocytes with distinctive nuclei. HL is classified into four subtypes based on histopathology, immunophenotype, and clinical presentation.

**Why the Correct Answer is Right:**
CD15 and CD30 are two common markers used to identify RS cells in Hodgkin lymphoma. CD15 is a pan-leukocytic marker, typically expressed in Hodgkin lymphoma, but it is not specific for RS cells. CD30, also known as Ki-1 antigen, is expressed in most Hodgkin lymphomas, except for one subtype.

**Why Each Wrong Option is Incorrect:**

A. **Lymphocyte-rich Hodgkin lymphoma**: This subtype consists of >50% RS cells and is positive for both CD15 and CD30.

B. **Lymphocyte-depleted Hodgkin lymphoma**: This subtype consists of <20% RS cells and is negative for both CD15 and CD30. C. **Mixed cellularity Hodgkin lymphoma**: This subtype consists of RS cells mixed with other lymphoid cells and is positive for both CD15 and CD30. D. **Nodular sclerosis Hodgkin lymphoma**: This subtype consists of RS cells in a background of dense fibrosis and is positive for both CD15 and CD30. **Clinical Pearl:** Understanding the immunophenotype of Hodgkin lymphoma helps in accurate classification and treatment planning. CD15 and CD30 positivity are crucial for the diagnosis of Hodgkin lymphoma, while CD20 positivity rules out non-Hodgkin lymphomas. Adequate knowledge of lymphoma classification systems, such as the Revised European-American Lymphoma (REAL) classification and the World Health Organization (WHO) classification, is essential for accurate diagnosis and treatment planning. **Why the Correct Answer is Right**: Lymphocyte-depleted Hodgkin lymphoma is a rare subtype of Hodgkin lymphoma characterized by the absence of RS cells, but presence of Reed-Sternberg cells and other lymphoid cells. These cells express CD15 and CD30, which are negative in the lymphocyte-depleted subtype. **Why Each Wrong Option is Incorrect**: A. Lymphocyte-rich subtype has a high percentage of RS