Diagnosis: Mastocytosis (Urticaria pigmentosa)

On physical examination, the patient had multiple 
hyperpigmented plaques over the trunk, chest, abdomen, and back.

Rubbing the lesions produced a hive-like wheal.
(Positive Darier's sign).

There was an intact fluid filled vesicle on the anterior chest.  

The biopsy was done to confirm a clinical diagnosis of
urticaria pigmentosa.

The Leder stain is a histochemical method for the detection of 
the enzyme chloracetate esterase which is found in granulocytes,
including mast cells (tissue basophils)and their precursors.
(See:Leder LD Am J Dermatopathol 1979 Spring;1(1):39-42 
The chloroacetate esterase reaction. A useful means 
of histological diagnosis of hematological disorders 
from paraffin sections of skin.)

The Leder stain is a sensitive technique 
that is interpreted in the context of the 
clinicopathologic setting and correlation with 
the H+E morphology. In our experience, this is 
more sensitive and often easier to interpret 
than a Giemsa stain; although, we also 
do sometimes use the latter method as well. 

Immunohistochemical methods are also 
now available. (see below) We do not have 
any personal experience with those antibodies

Links to PubMed References

The skin in mastocytosis:
Pediatric mastocytosis:
Hematopathology of bone marrow in pediatric mastocytosis:
Treatment of mastocytosis: an overview:
Immunohistochemistry - Anti-tryptase: An alternative diagnostic staining technique
Mast cells in cutaneous mastocytosis: An immunohistochemical study.


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