Table 2.

Overview of C4.4A, Haldisin, CK1, CK10, CK5 and CK14 expression patterns in precursor and invasive lesions.

Lesion	No. of cases	C4.4A	Haldisin	CK1/10	CK5/14
Actinic keratosis Precursor lesion of squamous cell carcinoma mostly through carcinoma in situ	5	5/5: No alteration	4/5: Sites with loss of or attenuated expression	5/5: Complete loss or attenuated expression	5/5: Expression confined to basal and suprabasal layers.
Keratoacanthoma In early stage infiltrating, despite being a benign lesion	7	4/7: Attenuated expression in core and high expression in invasive front	7/7: Sustained expression in differentiated layers	7/7: Sustained expression in most differentiated layers and complete loss or attenuated expression in core	6/7: Attenuated (CK5: partial loss) expression in core and high expression in invasive front
Carcinoma in situ Pre-cancerous	5	3/5: Attenuated expression in lower suprabasal layers	4/5: Complete or partial loss of expression	3/5: Attenuated or partial loss of expression	5/5: Expression primarily in the basal layer
Basal cell carcinoma Malignant tumor Low metastatic risk 1 keratotic, 1 nodular, 1 nodular/cystic, 3 superficial	6	5/6: Tumor islands with expression. Four of the cases have overlapping CK1 expression	6/6: Negative tumor 1/6: Weak expression in a few cells around keratin pearls	5/6: CK1 expression in tumor islands 1/6: CK10 expression in tumor islands	6/6: Expression in tumor cells
Squamous cell carcinoma Malignant tumor Low metastatic risk	6	4/6: Attenuated expression in tumor core and recovery of high expression in the invasive front	6/6: Loss of expression and only expression in differentiated cells often surrounding keratin pearls	6/6: Loss of expression or expression in a few single cancer cells or tumor cell islands often surrounding keratin pearls	5/6: Attenuated (CK5: partial loss) expression in tumor core and recovery of high expression in the invasive front
Normal nevi	7	7/7: Negative (3 cases were examined by ISH)	7/7: Negative	ND	ND
Malignant melanoma High metastatic risk 5 superficial spreading 4 lentigo maligna 4 nodular 3 desmoplastic	16	12/16: Negative tumor 4/16: Very weak expression in minor parts of the tumor of 2 superficial spreading and 2 nodular malignant melanomas (5 superficial and 1 nodular malignant melanoma were examined by ISH)	16/16: Negative tumor	ND	ND
Metastases from melanomas	5	5/5: Negative (4 cases were examined by ISH)	5/5: Negative	ND	ND

Tissue sections of precursor and invasive lesions were stained for C4.4A, Haldisin, CK1, CK10, CK5 and CK14. The lesion type, the number of examined cases as well as a description of the main findings are listed in the table. The numbers of cases with the described staining patterns are indicated. ISH, in situ hybridization.