Section 18: Neoplasms of the Skin Flashcards
What is mastocytosis?
The proliferation and accumulation of mast cells in the skin and/or other tissues.
Childhood-onset mastocytosis, prior to puberty, 70% by 6 months of age, benign, remits
Adult-onset mastocytosis, 30’s or 40’s, persists w/ systemic involvement
Mutations in mastocytosis?
Somatic activating mutation (codon 816) in the gene encoding the KIT tyrosine kinase receptor expressed on mast cells
What is the classification of mastocytosis?
Cutaneous mastocytosis, or Urticaria pigmentosa, variants?
Two major variants:
– Monomorphic small lesions (“urticaria pigmentosa”) that can occur in adults or children and tend to persist
– Polymorphic larger lesions (some >1 cm) that most often develop in infancy and typically resolve by adolescence
Darier sign in mastocytosis. An infant with extensive cutaneous involvement
Urticaria pigmentosa usually favors the?
Trunk, proximal extremities, sapring the face, palms and soles
Telangiectasia macularis eruptiva perstans (TMEP)?
A rare adult variant that presents with telangiectatic macules and patches without significant hyperpigmentation, often with a minimal Darier sign.
Diffuse cutaneous mastocytosis primarily in infants. Diffusely infiltrated doughy skin with multiple erosions and a leathery texture. Flushing, blistering, and erosions are common, but spontaneous resolution usually occurs.
Ddx: Epidermolysis bullosa, autoimmune bullous dermatoses
What causes systemic manifestations of mastocytosis?
Release of mast cell mediators such as histamine can lead to systemic symptoms, which range from flushing to abdominal pain and diarrhea to lightheadedness and syncope
Major criteria for diagnosing systemic mastocytosis?
Multifocal dense infiltrates of mast cells (aggregates of ≥15 mast cells) in bone marrow or extracutaneous tissues
Minor criteria for diagnosing systemic mastocytosis?
- > 25% of mast cells in bone marrow samples or extracutaneous tissues are spindle-shaped or otherwise atypical
- Extracutaneous mast cells (CD117+) express CD2, CD25, or both (often bone marrow; determined via flow cytometry)
- Presence of c-KIT codon 816 mutation in blood, bone marrow, or extracutaneous tissues
- Serum total tryptase level is persistently >20 ng/ml (unless there is an associated clonal myeloid disorder, in which case this parameter is not valid)
Adults with systemic mastocytosis occassionally develop?
Osteoporosis
Osteosclerosis
Hepatosplenomegaly
Lymphadenopathy
Infiltration of the GI tract
Medications that trigger mastocytosis?
Aspirin, NSAIDs, morphine/codeine, anticholinergics etc.
Treating systemic sx’s in mastocytosis?
Cetirizine (high dose up to 40 mg)
Sedating at night, especially if they have upper GI symptoms (nausea, epigastric pain, vomitting) or cromolyn sodium (topical or oral) to reduce pruritus.
Topical therapy with a potent CS or cal- cineurin inhibitor, narrowband UVB photo- therapy, or omalizumab may be helpful in patients with refractory symptoms.
For aggressive symptoms of mastocytosis?
Aggressive systemic disease can be treated with agents such as:
1- Midostaurin (a multi-kinase/KIT inhibitor)
2- Imatinib (for some KIT mutations)
3- Cladribine
Which KIT receptor or AA changes provide imatinib-responsive disease?
Del419
K509
M541L
F522C
V560G
Maculopapular cutaneous mastocytosis “urticaria pigmentosa” Variable numbers of tan to brown macules, papules, and plaques are evident
Mastocytoma’s in infants
A - The leathery appearance of the skin and erosions
B - Subtle, tan papule on the scalp
Bullous mastocytosis. A Tense bullae on the wrist and flaccid bullae on the dorsal hands as well as pink plaques on the trunk in a 1-month-old infant. C Blister superimposed on a plaque.
Subtle erosions seen in cutaneous mastocytosis
