• All IHC stains will include a positive control tissue

• The bacteriolytic enzyme acts on walls of susceptible micro-organisms by cleavage of the bond between N acetyl muramic acid and N acetylglucosamine
• Useful in the workup of myeloid leukemias. Variable staining pattern seen in normal and leukemic myeloblasts and monoblasts (range from positive to negative in various studies)^1,2,4,6
• Lymphoid cells and their malignancies are negative for lysozyme
• Natural killer cells, red blood cells, erythroblasts and megakaryocytes are also negative¹
• Majority of epithelioid histiocytes associated with toxoplasmic lymphadenitis and granulomatous diseases show moderate to strong positivity for intracellular lysozyme ¹
• Lysozyme is a well known marker of benign reactive macrophages in tissue sections, but appears not to be a reliable marker of malignant histiocytes ²
• A large number (26 of 29 and 2 of 2) of extramedullary myeloid cell tumors (granulocytic sarcomas) show strong cytoplasmic staining with lysozyme (helpful in diagnosing cases which lack histologic evidence of granulocytic differentiation and may be negative with CAE)^3-5
• Focal positivity for lysozyme seen in some cases of granular cell tumor

Submit a formalin-fixed, paraffin embedded tissue block

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

• Lysozyme (Muramidase) is an intracellular enzyme found in myeloid cells, monocytes and their precursors, histiocytes and some body fluids and secretions
• Lysozyme is present in a variety of normal human tissues

 
Staining pattern

• Diffuse granular cytoplasmic

References

1. AJP 89:351-366, 1977.
2. AJH 21:99-109, 1986.
3. Archives of Pathol and Lab Medicine 120:62-67, 1996.
4. Cancer 71:124-32, 1993.
5. AJCP 102:55-60, 1994.
6. AJCP 67:481-484, 1977.