1. Mastocytosis

2. An Bras Derm. 84 nO. 3, 2OO9

3. An Bras Derm. 84 nO. 3, 2OO9

5. An Bras Derm. 84 nO. 3, 2OO9
In tissues, mast cells differentiate into two subgroups: mucosal mast cells (MMC) and connective tissue mast cells (CTMC)

10. Criteria for diagnosis of cutaneous & systemic mastocytosis

11. In childhood patients with MIS, a bone marrow investigation is not recommended unless serum tryptase levels are very high (>100 ng/ml) or the blood count and/or other clinical findings and symptoms suggest the presence of a hematologic neoplasm

12. Note:
In those with normal or slightly increased tryptase level and a REMA score <2, it is helpful to examine peripheral blood cells for the presence of KIT D816V
In patients in whom typical signs and symptoms (e.g. osteoporosis, histamine-induced symptoms, increased histamine metabolite excretion, unexplained anaphylaxis) or KIT D816V are detected, a BM examination should be performed.

13. Modern pathology 24:1157, 2O11
algorithm for the diagnosis and classification of different subtypes of mastocytosis

18. Algorithm for classification of systemic mastocytosis (SM).

19. Mastocytosis

20. Darier sign
Rubbing an area of skin affected by mastocytosis may also activate the mast cells. The rubbed skin becomes reddened, swollen and itchy within a few minutes (Darier sign). In young children, the rubbed area may later blister

21. Solitary mastocytoma & the effect of rubbing

22. Darier’s sign
Darier's sign: stroking skin releases histamine, causing hives
Dermatographism: dermal edema resembling hives due to stroking with pointed instrument

23. Urticaria Pigmentosa

24. Maculopapular cutaneous mastocytosis

25. Urticaria Pigmentosa on the face

26. Diffuse cutaneous mastocytosis

27. Telangiectatic cutaneous mastocytosis

28. Mastocytosis bullosa

29. Mastocytosis

30. Mastocytosis Hyperpigmentation of keratinocytes in the basal layer and metachromasia of mast cells (Toludine blue)

31. Mastocytosis

32. skin lesion of urticaria pigmentosa
skin lesion of urticaria pigmentosa. Hyperpig- mented basal layer and scattered cuboidal mast cells in the dermis, especially at the perivascular area

33. Urticaria pigmentosa A basket-weave cornified layer
Increased pigmentation of the basal layer
A thickened papillary dermis containing many mast cells which are characterized by the large oval centrally located nuclei and abundant basophilic cytoplasm
Scattered eosinophils
A superficial perivascular infiltrate of lymphocytes, histiocytes and mast cells
Widely dilated blood vessels of the superficial plexus

34. An Bras Derm. 84 nO. 3, 2OO9

35. Telangiectazia maculare eruptiva perstans

37. This photograph illustrates the aberrant membrane associated reactivity for CD25 by neoplastic mast cells of the case of indolent systemic mastocytosis illustrated in the previous, related photograph

38. Systemic mastocytosis
Systemic mastocytosis. Mast cells usually demonstrate metachromatic granules when stained with Giemsa or toluidine blue. However, the most specific methods for identification in tissue sections is immunohistochemical staining for tryptase/chymase and CD117, and for neoplastic mast cells, CD2 and CD25.

39. Systemic mastocytosis
Systemic mastocytosis. Mast cells usually demonstrate metachromatic granules when stained with Giemsa or toluidine blue. However, the most specific methods for identification in tissue sections is immunohistochemical staining for tryptase/chymase and CD117, and for neoplastic mast cells, CD2 and CD25

40. A dense infiltrate of mainly spindle-shaped slightly hypogranular mast cells in a bone marrow specimen of a patient with indolent systemic mastocytosis

41. Systemic mastocytosis
Systemic mastocytosis. The cells may have bland nuclei with moderate amounts of pale cytoplasm, spindled shapes that resemble fibroblasts, or lobulated nuclei with abundant clear cytoplasm. The latter cells may resemble monocytes or histiocytes, and are more commonly seen in aggressive mast cell lesions

42. Perivascular accumulation of mast cells stained for mast cell tryptase in the bone marrow of a patient with systemic mastocytosis.

43. Perivascular accumulation of mast cells stained for CD117 in the bone marrow of a patient with systemic mastocytosis

44. Perivascular accumulation of mast cells stained for CD25 in the bone marrow of a patient with systemic mastocytosis.

45. Mastocytosis - Skeleton - X-ray

46. Mastocytosis - Skeleton - X-ray

47. Signal transduction events initiated by Kit and Fc_RI leading to specific mast cell responses, and the integration of these pathways for the synergistic enhancement of mast cell mediator release

48. Bone marrow mast cell immunophenotyping in systemic mastocytosis reveals abnormal CD25 expression. Abbreviations: otherwise specified; CMML, chronic myelomonocytic leukemia; HES, hypereosinophilic syndrome.