All IHC stains will include a positive control tissue

• Factor XIIIa is used to identify dermal dendrocytes as in dermatofibromas (DF)
• This antibody is useful to distinguish DF from DFSP; DFSP shows no or very little reactivity for Factor XIIIa, but stains for CD34
• Factor XIIIa will also stain other types of fibrohistiocytic tumors, including atypical fibroxanthoma, fibrous papules of the nose, juvenile xanthogranulomas, and malignant fibrous histiocytoma
• Factor XIIIa staining has also been reported in atypical fibroblasts in radiation dermatitis

Submit a formalin-fixed, paraffin-embedded tissue

Formalin-fixed, paraffin-embedded (FFPE) tissue block

FFPE tissue section mounted on a charged, unstained slide

Ambient (preferred)

• Unlabeled/mislabeled block
• Insufficient tissue
• Slides broken beyond repair

Immunohistochemical staining and microscopic examination

If requested, an interpretive report will be provided

Specifications

• Factor XIII is a beta globulin found in plasma, and is a thrombin-activated calcium-dependent fibrin-stabilizing factor

• Factor XIIIa is an antibody to the A-subunit of human coagulation Factor XIII

• The Factor XIIIa antibody does not react with Factor XIII B-subunit

• Factor XIIIa also reacts with a population of dermal dendritic cells, and other similar connective tissue cells (it is not known whether this antibody is labeling a cross-reacting protein or actual Factor XIIIa in these cells)

• Factor XIIIa also reacts with some macrophages (including Kupffer cells of the liver)

Staining pattern

• Cytoplasmic

References

1. Abenoza P et al: CD34 and Factor XIIIa in the differential diagnosis of DF and DFSP. Am J Dermatopathol 1993, 15(5):429-434

2. Cerio R et al: Characterization of Factor XIIIa positive dermal dendritic cells in normal and inflamed skin. Br J Dermatol 1989;121;421-431