Table 1.
Summary of CD99 expression in normal adult epidermis and skin appendages
| Immunoreactivity | ||
|---|---|---|
| Epidermis | Basal cells | ++ |
| Prickle cells | + | |
| Granular cells | – | |
| Horny cells (cornified cells) | – | |
| Hair follicle | Bulge | ++ |
| Cortex | – | |
| Cuticle | – | |
| Inner root sheath–lower | + | |
| Outer root sheath | ++ | |
| Glassy membrane | – | |
| Sweat glands | ||
| Eccrine secretory coil | Inner dark cells | ++a |
| Outer clear cells | – | |
| Apocrine secretory acinus | Secretory cells | +/–a |
| Excretory duct | Inner layer cells | +a |
| Outer layer cells | ++ | |
| Sebaceous glands | Mature sebocytes | – |
| Basal cells | ++ |
++, consistently strong and complete membranous staining; +, consistently weak to moderate staining; +/–, variable staining; –, negative.
a
Apico-luminal surfaces are negative for CD99.