Mast cell tumor pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Pathophysiology
- A mast cell originates from the bone marrow and is normally found throughout the connective tissue of the body. You can find mast cells in skin, lymph nodes, internal organs (such as the liver and spleen) and the linings of the lung, stomach, and intestine.
- It is a normal component of the immune system and as it releases histamine it is associated with allergic reactions.
- Mast cell granules contain histamine, heparin, platelet-activating factor, and other substances.[1]
- In systemic mastocytosis, abnormal proliferation and microscopic infiltration of mast cells involves skin, bone marrow, gastrointestinal tract, liver, and spleen.[2]
- It is thought that the effects of mastocytosis relate at least in part to mediator release.
- Mast cells express a cell surface receptor, c-kit (CD117), which is the receptor for stem cell factor. In laboratory studies, stem cell factor appears to be important for the proliferation of mast cells.
- Mutations of the c-kit receptor, leading to uncontrolled stimulation of the receptor, is a cause for the disease.
- The presence of too many mast cells, or mastocytosis, can occur in two forms—cutaneous and systemic. The most common cutaneous form is also called urticaria pigmentosa, which occurs when mast cells infiltrate the skin. Systemic mastocytosis is caused by mast cells accumulating in the tissues and can affect organs such as the liver, spleen, bone marrow, and small intestine.[3]
- The D816V point mutation within the tyrosine kinase Kit (c-Kit) that is detected in 80% of cases is considered a driver mutation causing the permanent receptor activation and consequent proliferation, and thus neoplastic expansion of the mutated mast cell clone.
Genetics
Genes involved in the pathogenesis of mast cell tumor include: The following genes are involved in the pathogenesis of mast cell tumor:
- KIT
- RAS
- JAK2
- TET2
- DNMT3A
- ASXL1
- CBI
Microscopic Pathology
- Cells in the superficial/mid dermis that are:[4]
- Lymphocyte-like with more cytoplasm that is granular
- Cells may have spindled or stellate morphology
- Tend to be more abundant around vessels
- Eosinophils may present
References
- ↑ Brière C (2002). "Use of a reverse saphenous skin flap for the excision of a grade II mast cell tumor on the hind limb of a dog". Can Vet J. 43 (8): 620–2. PMID 12170840.
- ↑ Mastocytosis. Dr Alexandra Stanislavsky. Radiopaedia.org 2015. http://radiopaedia.org/articles/mastocytosis Accessed on February 29, 2016
- ↑ Mastocytosis. National cancer institute. https://www.niaid.nih.gov/topics/mastocytosis/Pages/Default.aspx accessed on March 1st, 2016
- ↑ Mastocytosis. Libre Pathology. http://librepathology.org/wiki/Mastocytosis accessed on March 1st, 2016