ABSTRACT
Cutaneous cysts 837 Bronchogenic cyst 837 Cutaneous ciliated cyst 837 Cutaneous follicular cysts 837 Dermoid cysts of the skin 838 Digital mucous/myxoid cyst 838 Epidermal cysts 839 Epidermoid cysts 839 Eruptive villus hair cysts 839 Hidrocystomas 839 Median raphe cyst of the penis 840 Steatocystoma multiplex 840 Tricholemmal cyst 840
Epithelial tumors 841 Epidermal tumors, benign 841
Clear cell acanthoma 841 Linear epidermal nevus 841 Seborrheic keratosis 842 Solar lentigo 844 Squamous papilloma 845 Verrucae 845
Epidermal tumors, in-situ malignancy 847 Actinic keratosis 847 Bowen’s disease 848
Epidermal tumors, malignant 849 Basal cell carcinoma 849 Squamous cell carcinoma, common variant 853 Squamous cell carcinoma, other variants 853
Epidermal tumors, uncertain malignant potential 854 Keratoacanthoma 854
Skin appendage tumors, benign: hair follicle-derived tumors 854 Dilated pore of Winer 854 Fibrofolliculoma 855 Follicular nevi 856 Pilar sheath acanthoma 856 Pilomatrixoma 856 Proliferating pilar tumor 857 Trichoadenoma 857 Trichoepithelioma 858 Trichofolliculoma 859 Trichogenic tumors 860 Tricholemmoma 862 Warty dyskeratoma 862
Skin appendage tumors, benign: sebaceous gland-derived tumors 862 Hamartoma/hyperplasia: folliculosebaceous cystic
hamartoma 862 Nevus sebaceous (sebaceous nevi) 863 Sebaceoma 864 Sebaceous adenoma 864
Skin appendage tumors, benign: sweat gland-derived tumors 865 Chondroid syringoma 865 Cylindroma 867 Eccrine spiradenoma 868 Hidradenoma (clear cell hidradenoma; acrospiroma) 869 Hidradenoma papilliferum 870 Poromas 870 Syringocystadenoma papilliferum 871 Syringoma 872
Skin appendage tumors, malignant: hair follicle-derived tumors 873 Pilomatrix carcinoma 873 Tricholemmal carcinoma 873
Skin appendage tumors, malignant 874 Neuroendocrine carcinoma (Merkel cell carcinoma) 874
Skin appendage tumors, malignant: sebaceous gland-derived tumors 874 Sebaceous carcinoma 874
Skin appendage tumors, malignant: sweat gland-derived tumors 875 Adenoid cystic carcinoma 875 Aggressive digital papillary adenoma/carcinoma 875 Hidroadenocarcinoma/malignant transformation of
cylindroma/spiradenocarcinoma 876 Microcystic adnexal carcinoma 876 Mucinous carcinoma 877 Porocarcinoma 878 Primary extramammary Paget’s disease 879
Melanocytic lesions, benign 879 Common nevi 879
Junctional, intradermal and compound nevi 879 Lentigo 881 Spitz nevi and variants 881
Variant nevi 883 Ancient nevus 883 Balloon cell nevus 883 Blue nevus 883 Combined nevus 884 Congenital nevi 885 Deep penetrating nevus (plexiform spindle cell nevus) 885 Halo nevus 886 Nevus after UV irradiation 886 Pigmented spindle cell nevus 886 Pseudo-melanoma (persistent nevus) 887 Special-site nevi and variants 887
Melanocytic lesions, malignant 888 Common types of melanoma 888
Acral lentigenous melanoma in situ 888 Lentigo maligna 889
Skin biopsies comprise a large proportion of the workload in any surgical pathology department. Amongst the malignant tumors, basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) rank number one in their frequency. These tumors usually create no or very little diagnostic difficulties. Malignant melanoma (MM) is much less frequent, but creates great
overdiagnosed or completely misinterpreted on hematoxylin and eosin (H&E) sections, with possible dire clinical consequences. However, with the current availability of immunohistochemistry in most pathology departments, this problem may be lessened. Other malignant skin tumors, such as sarcomas, skin appendage tumors and lymphomas are rare.
