Systemic Mastocytosis : Lymph Node

Comments:
Lymph Node in Systemic Mastocytosis (SM): Normal and reactive lymph nodes contain a large number of mast cells (MCs) in the sinuses; hence the number, location and distribution of MCs are important in diagnosing lymph node involvement in SM.

The diagnostic finding is presence of compact paracortical MC infiltrates. In some cases, the MC infiltrates are predominantly intrasinusoidal. The infiltrates may be indistinct on routine H&E stains and visualized only with the help of tryptase of CD25 immunostains.