Comparison with Normal Lymph Node

Answer: Lymphoid tissue. The resected mass was an enlarged lymph node with unusual features.

Figure 1. Unknown Case

Compare the enlarged node to a reactive lymph node in figure 2 below with respect to:

Node architecture

Germinal center size

Interfollicular lymphoid tissue

See answers after next image.

Figure 2. Reactive Lymph Node



Answers: The nodal architecture of the mass resembles that of the reactive node with clearly-defined follicles with germinal centers and surrounding interfollicular tissue. Compared to the reactive node, the germinal centers of the mass are smaller and less blue; i.e., fewer lymphoid cells. The interfollicular lymphoid tissue of the mass is pinker (fewer lymphocytes) because of a marked proliferation of blood vessels (see below).


Figure 3. High-power View of Resected Mass

Compare the lesion to its reactive counterpart in figure 4 below with respect to:

Germinal center (GC) size

Mantle zone (follicular lymphocytes around GC)

Interfollicular tissue

Outline the lymphoid follicle.

See answers after next image.




Figure 4. High-power View of Reactive Lymph Node

Outline two germinal centers.

Find the subcapsular sinus, which contains some lymphocytes. Three sites are marked.

Answers: Compared to the reactive lymph node (figure 4), the nodal mass has smaller, atrophic, or regressed germinal centers. Note the presence of several blood vessels in the germinal center. These are not normally this prominent.

Compared to the reactive lymph node, the mantel zone of the nodal mass is larger and composed of lymphocytes in concentric layers. The interfollicular tissue has large numbers of blood vessels with thickened walls.

The normal subcapsular and interfollicular sinuses of the reactive lymph node (the drainage pathway of the afferent lymphatics to the node) are usually obliterated by the disease in the resected mass.

What is the differential diagnosis? Answer What is the diagnosis? Answer




























Histologic differential diagnosis: Castleman's disease of the hyaline-vascular type (CD-HV) is the main consideration, but a node with a non-specific, reactive, follicular hyperplasia should also be considered. With reactive hyperplasia, usually only a few follicles show the small GCs seen much more frequently in CD-HV. Other features supporting CD are the solitary nature of the enlarged node and the mediastinal location.





























Lymphoid follicle. The GC is the collection of pale-staining cells at its center. The MZ consists of concentrically-arranged lymphocytes. Both GC and MZ lymphocytes are mostly B-cells.































Nodal subcapsular sinus. Afferent lymphatics drain into this sinus, which communicates with interfollicular sinuses not well seen here. Efferent lymphatics exit at the hilus.


























Germinal center with a mixture of lymphocytes and large, pale dendritic (antigen-presenting) cells.





























Germinal center. It is smaller than the other one probably because of the plane of section. It is also composed of small lymphocytes and large, pale dendritic cells.



























Diagnosis: Castleman's disease, localized, hyaline-vascular type, also known as angiofollicular lymph node hyperplasia. The patient had no associated disease, and multicentric disease was not detected clinically or radiographically.

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