Mastocytosis.

Area of Science:

• Hematopathology
• Hematologic Neoplasms
• Mast Cell Disorders

Background:

• Mastocytosis is a rare neoplastic disorder characterized by abnormal mast cell proliferation.
• The disease spectrum ranges from indolent cutaneous forms to aggressive systemic mastocytosis with associated hematologic neoplasms (SM-AHN).
• Accurate diagnosis is critical due to the advent of targeted therapies, particularly those aimed at KIT mutations.

Purpose of the Study:

• To review and discuss the spectrum of mastocytosis and related diseases, including morphologic mimics.
• To focus on recent updates and relevant findings for pathologists in diagnosing mastocytosis.
• To emphasize the implications of accurate classification for patient management and targeted treatment.

Main Methods:

• A panel reviewed 99 cases encompassing cutaneous mastocytosis and SM-AHN.
• Cases covered the full spectrum of mastocytosis, including rare subtypes and extramedullary involvement.
• Representative cases were used to illustrate diagnostic challenges and findings.

Main Results:

• Mastocytosis is a heterogeneous neoplasm with diverse clinical presentations, despite a common KIT mutation (e.g., D816V).
• The reviewed cases demonstrated the wide variability in disease presentation and organ involvement.
• Morphologic mimics and challenging diagnostic scenarios were identified.

Conclusions:

• Accurate diagnosis and classification of mastocytosis are paramount for guiding therapy and interventions.
• Understanding the clinical, pathologic, and genetic features is essential for appropriate diagnostic testing.
• This knowledge aids pathologists in achieving a correct diagnosis for this rare and complex disease.