Cutaneous Mastocytoma : Tryptase

Comments:
Immunohistochemical Profile of Mastocytoma: Neoplastic mast cells express CD33, CD5, CD68, KIT/CD117, tryptase (shown here) and chymase. CD117 is highly sensitive but less specific marker for mast cells. Chymase is highly specific but not as sensitive.

Neoplastic mast cells show aberrant expression of CD25 and/or CD2. This is helpful in differentiating them from normal mast cells. CD2 is more readily detected by flow cytometry. More recently CD30 has also been established as a novel aberrant marker for neoplastic mast cells especially in advanced systemic mastocytosis. Mast cells don't express most B- and T-cell markers and are negative for myelomonocytic markers CD14, CD15, and CD16.

Image courtesy of: Miguel Reyes-Mugica, MD, Chief of Pathology, Univ. of Pittsburgh Children's Hospital, Pittsburgh, Pennsylvania, USA.