Lymphomas: Pathology review

At the family medicine center, there is a 25 year old male, named Hogan, who came in because of a painless non-erythematous mass on his neck. Next to Hogan, there is a 30 year old male immigrant from Africa, named Burak, who has noticed a painless mass on his jaw. He also complains of drenching night sweats, and unexplained weight loss over the last few months. Biopsy is ordered for both people. In Hogan’s there’s binucleated B cells surrounded by mainly lymphocytes. Burak’s biopsy showed numerous lymphocytes with some tingible-body macrophages. CBC is normal for both.

Both Hogan and Burak have lymphoma. Lymphomas are tumors derived from lymphocytes, which are B and T cells. They can be broadly grouped into two categories; Hodgkin and non-Hodgkin lymphomas.

In contrast, non-Hodgkin lymphomas don’t have Reed-Sternberg cells can sometimes spread non-contiguously, and can involve extranodal sites like the skin, gastrointestinal tract, and brain. Non-Hodgkin’s lymphomas can occur in both children and adults. Finally, overall prognosis is better with Hodgkin lymphomas.

Let’s start by looking at Hodgkin lymphoma. This type of lymphoma typically arise from B-cells and spread in a contiguous manner, meaning it spreads to nearby lymph nodes, and rarely involve extranodal sites. It has a bimodal age distribution, affecting young adults in their 20s and adults older than 60 years of age. Histologically, it’s characterized by the presence of Reed-Sternberg cells and for your exams, remember that these are binucleated, neoplastic B cells that look kind of like owl eyes. The large mononuclear version of Reed-Sternberg cells are called Hodgkin cells. These abnormal, neoplastic cells are usually surrounded by non-neoplastic inflammatory cells, mostly T cells, and sometimes eosinophils. They can also activate fibroblasts, which secrete collagen.

Okay, now Hodgkin lymphoma includes two major subgroups, the first and more common is classical Hodgkin lymphoma, or cHL. In classical Hodgkin lymphoma, neoplastic cells don’t express CD45 or CD20, which are seen on normal B-cells, but they do express CD15 and CD30.

Classical Hodgkin lymphoma can be further divided into four histologic subtypes based on the type of inflammatory cells and whether fibrosis is present. Nodular sclerosis is the most common subtype and the neoplastic cells are surrounded by collagen that create nodules. Also, a unique Reed-Sternberg cell, called a lacunar cell can be seen. When the tissue is fixed in formalin, the cytoplasm shrinks and it makes the nucleus look like it’s sitting in the middle of a lake, or lacunae. Now, the second most common subtype is mixed cellularity Hodgkin lymphoma and the neoplasm is mixed with many different types of immune cells like eosinophils, neutrophils, lymphocytes, plasma cells, and histiocytes. The third subtype is lymphocyte-rich Hodgkin lymphoma, and it’s named for having mostly lymphocytes surround the Reed-Sternberg cells. It generally has the best prognosis of all of the classical Hodgkin lymphoma subtypes. The fourth type is lymphocyte-depleted Hodgkin lymphoma, and it’s the least common type. It’s named for the lack of normal lymphocytes and the abundance of Hodgkin and Reed-Sternberg cells. Mixed cellularity and lymphocyte-depleted Hodgkin lymphoma are seen more commonly in immunocompromised patients.