Preface xv Acknowledgments xvii 1 EPIDERMIS 1 Nevi 2 Epidermal Nevus 2 Variant: Inflammatory Linear Verrucous Epidermal Nevus (ILVEN) 3 Keratoses 4 Seborrheic Keratosis (SK) and Variants 4 Variant: Acanthotic Seborrheic Keratosis 4 Variant: Reticulated, Pigmented Seborrheic Keratosis 6 Variant: Flat Seborrheic Keratosis 6 Variant: Papillomatous Seborrheic Keratosis 7 Variant: Activated (Irritated) Seborrheic Keratosis 7 Variant: Dermatosis Papulosa Nigra 7 Variant: Melanoacanthoma (Pigmented Seborrheic Keratosis) 8 Variant: Clonal (Intraepidermal) Seborrheic Keratosis (Borst- Jadassohn) 9 Variant: Seborrheic Keratosis with Monster Cells (Bowenoid) 10 Variant: Hyperkeratotic Seborrheic Keratosis (Stucco Keratosis) 11 Confluent and Reticulate Papillomatosis (Gougerot and Carteaud) 12 Reticulate Pigmented Anomaly of the Flexures (Dowling-Degos Disease) 13 Acanthosis Nigricans 14 Solar (Actinic) Keratosis 15 Variant: Acantholytic Solar Keratosis 16 Variant: Atrophic Solar Keratosis 16 Variant: Lichen Planus?Like Solar Keratosis 17 Variant: Hypertrophic (Bowenoid) Solar Keratosis 18 Cornu Cutaneum 18 Acanthomas, Non?Viral 19 Solar Lentigo 19 Callus, Factitial Acanthoma 20 Knuckle Pads (Chewing Pads) 21 Pale (Clear) Cell Acanthoma 22 Large Cell Acanthoma 23 Differential Diagnosis: Epidermolytic Acanthoma 24 Differential Diagnosis: Congenital Ichthyosiform Erythroderma 25 Acantholytic Acanthoma 26 Warty Dyskeratoma 27 Porokeratoma (Porokeratosis Mibelli) 30 Acanthomas, Viral 31 Verruca Vulgaris 31 Variant: Verruca Plana 33 Variant: Condyloma Acuminatum 34 Bowenoid Papulosis 35 Acrokeratosis Verruciformis (Hopf) 37 Molluscum Contagiosum 38 "Pseudocarcinomas" and Neoplasms with Intermediate Malignant Potential 40 Keratoacanthoma (KA) 40 Epithelioma Cuniculatum (Verrucous Carcinoma) (EC/VC) 44 Papillomatosis Cutis Carcinoides 45 Florid Papillomatosis of the Oral Cavity (Oral Verrucous Carcinoma) 46 Buschke-Löwenstein Tumor (Giant Condyloma) 47 Malignant Epidermal Neoplasms 48 Bowen''s Disease (Carcinoma in situ) 48 Variant: Clear Cell Bowen''s Disease 50 Variant: Cutaneous Horn (Cornu Cutaneum) on Bowen''s Disease 51 Variant: Pigmented (Anogenital) and Clonal Bowen''s Disease 52 Variant: Erythroplasia of Queyrat and Vulvar Intraepithelial Neoplasia 53 Basal Cell Carcinoma (BCC) 54 Variant: Nodular BCC 54 Variant: Infundibulocystic BCC 56 Variants of BCC With Ductal, Matrical or Sebaceous Differentiation 57 Variant: Superficial BCC 60 Variant: Pigmented BCC 61 Variant: Adenoid?Cystic BCC 62 Variant: Sclerodermiform (Morpheaform) BCC 64 Clinical Variants: Ulcerating BCCs 66 Histological Variants: Metatypic BCC with Squamoid Differentiation 67 Syndromatic BCC (Basal Cell Nevus Syndrome, Gorlin-Goltz) 69 Fibroepithelioma of Pinkus 70 Squamous Cell Carcinoma (SCC) 72 Variant: Well?Differentiated SCC 72 Variant: Acantholytic SCC (Epithelioma Spinocellulare Segregans of Delacretaz) 74 Variant: Myxoid SCC 76 Variant: Follicular (Infundibular) SCC 77 Variant: Spindle Cell (Fusicellular) SCC 78 Squamous Cell Carcinomas in Special Sites 79 2 ADNEXAL 85 Sweat Gland Differentiation 86 Nevi, Hyperplasias, and Benign Adnexal Neoplasms (BAN) 86 Eccrine Differentiation 86 Apocrine Differentiation 93 Malignant Adnexal Neoplasms 105 Eccrine Differentiation 105 Apocrine Differentiation 109 Sebaceous Differentiation 110 Hyperplasias and Hamartomas 111 Ectopic (Heterotopic) Sebaceous Glands (Fordyce Glands) 111 (Senile) Sebaceous Gland Hyperplasia 112 Nevus Sebaceous (Jadassohn) 113 Variant: Pilo?Sebaceous Hamartoma 114 Benign Neoplasms 114 Sebaceous Adenoma 114 Muir-Torre Syndrome 115 Sebaceous Epithelioma (Sebaceoma) 116 Malignant Neoplasms 118 Sebaceous Carcinoma 118 Hair Follicle Differentiation 119 Nevi, Hyperplasia, and Hamartomas 119 Hair Follicle Nevus 119 Conical Infundibular Acanthoma (Giant Dilated Pore of Winer) 120 Benign Neoplasms 121 Pilar Sheath Acanthoma 121 Trichilemmoma (Tricholemmoma) 122 Tumor of the Follicular Infundibulum (Infundibuloma) 124 Trichoepithelioma (Superficial Trichoblastoma) 125 Trichoblastoma (Trichoblastic Fibroma; Immature Trichoepithelioma) 127 Trichoepithelioma (Sclerosing Epithelial Hamartoma) 131 Trichofolliculoma (Folliculosebaceous Cystic Hamartoma) 133 Trichoadenoma (Nikolowski) 136 Pilomatricoma (Calcifying Epithelioma Malherbe) 137 Proliferating Trichilemmal (Pilar) Tumor (PTT) (Proliferating Trichilemmal Cyst) 138 Malignant Neoplasms 140 Malignant Pilomatricoma (Pilomatrical Carcinoma) 140 Trichilemmal Carcinoma 141 Trichoblastic Carcinoma 142 Pilosebaceous Mesenchyme 143 Benign Neoplasm 143 Trichodiscoma (Follicular Fibroma, Fibrofolliculoma, Perifollicular Fibroma) 143 3 PAGET''S DISEASE 145 Mammary Paget''s Disease 146 Extramammary Paget''s Disease 146 4 MELANOCYTES 149 Non?Neoplastic Hyperpigmentations 150 Ephelides (Genuine Freckles) 150 PUVA (Psoralen UVA) Lentigo 150 "Nevus" Spilus (Speckled Lentiginous Nevus; Café?Au?Lait Spot) 151 "Ink" Spot Lentigo (Reticulated Melanocytic Macule) 152 Senile Freckles (Solar [Actinic] Lentigo) 153 Mucosal Lentiginous Spots (Lip, Buccal, and Genital Mucosa) 154 Nevi 155 Common Acquired Melanocytic Nevi 155 Melanosis Neviformis (Pigmented Hairy Epidermal Nevus; Becker Nevus) 155 Junctional Nevus 156 Compound Nevus 157 Dermal Nevus 158 Variant: Miescher''s Nevus (Dermal Nevus) 160 Variant: Balloon Cell Nevus 161 Variant: "Activated" Acral (Lentiginous) Melanocytic Nevus 161 Variant: (Atypical) Genital Melanocytic Nevus 162 Variant: Halo Nevus (Leukoderma Centrifugum Acquisitum; Sutton Nevus) 163 Variant: Eczematoid Melanocytic (Meyerson''s) Nevus 165 Variant: Osteo?Nevus of Nanta 166 Variant: Combined Epithelioid Spitzoid Nevus, "Wiesner Nevus" (BAP-1 Deficient Epithelioid Melanocytic Tumor) 167 Variant: Recurrent (Persistent) Melanocytic Nevus (Pseudomelanoma) 167 Variant: Nevus in Pregnancy 168 Variant: Ancient Nevus 170 Blue Nevi 171 Common Blue Nevus 171 Common Blue Nevus 172 Dermal Melanocytosis 177 Nevus Fuscoceruleus (Ota; Ito; Mongolian Spot) 177 Spindle and/or Epithelioid Cell Nevus 178 Common Nevus of Spitz 178 Variants of Spindle and Epithelioid Cell Nevus 179 Variant: Pigmented Spindle Cell Nevus (Reed) 182 Benign Melanocytic Lesions with Peculiar Structural Features 183 Melanocytic Nevus with Clonal Proliferation 183 Atypical (Dysplastic) Melanocytic (Clark''s) Nevus (B?K Mole Syndrome) 185 Congenital Nevi, Small and Medium?Sized (1.5-20 cm) 186 Malignant Melanocytic Neoplasms 188 Lentigo Maligna Dubreuilh (Hutchinson''s Freckle) 188 Malignant Melanoma 189 Variant: Superficial Spreading Melanoma (SSM) 190 Variant: Lentigo Maligna Melanoma (LMM) 192 Variant: Nodular Melanoma (NM) 193 Variant: Acral Lentiginous Melanoma (ALM) 194 Variant: Melanoma in Large Congenital Melanocytic Nevus (LCMN) 196 Variant: Cutaneous Metastasis of Melanoma 197 Special Localisations of Malignant Melanoma 204 Tumor Thickness and Levels 205 Common Clinical Differential Diagnoses of Malignant Melanoma 205 5 CONNECTIVE TISSUE 207 Nevi 208 Connective Tissue Nevus (Shagreen Patch; Cobblestone Nevus; Nevus Collagenicus) 208 Fibrous Neoplasms 209 Soft Fibroma (Skin Tag; Acrochordon) 209 Perifollicular Fibroma (Fibrofolliculoma; Trichodiscoma) 210 Variant: Sclerotic Fibroma (Plywood Fibroma; Storiform Collagenoma) 211 Variant: Fibrous Papule of the Nose 212 Variant: Pleomorphic Sclerosing Fibroma with Multinucleated Cells 212 Keloid 213 Infantile Digital Fibromatosis (Inclusion Body Fibromatosis; Recurring Digital Fibrous Tumor of Children; Reye''s Tumor) 214 Malformations with Supernumerary Tissue Elements 216 Supernumerary Digit (Rudimentary Digit; Rudimentary Polydactyly) 216 Differential Diagnosis: Acral Acquired Fibrokeratoma 216 Accessory Tragus (Preauricular Tag) 217 Accessory Nipple (Ectopic Breast; Polythelia) 218 Fibrohistiocytic Neoplasms 218 Dermatofibroma (Benign Fibrous Histiocytoma; Fibroma Durum; Sclerosing Hemangioma) 218 Dermatofibrosarcoma Protuberans 227 Variant: Pigmented Dermatofibrosarcoma Protuberans (Bednar''s Tumor) 230 Variant: Giant Cell Fibroblastoma 231 Pleomorphic Dermal Sarcoma (PDS) 231 Miscellaneous Tumors 234 Epithelioid Sarcoma 234 Dermatomyofibroma 236 6 VESSELS 239 Hamartomas, Nevi, and Malformations 240 Phacomatosis Pigmentovascularis 240 Eccrine Angiomatous Hamartoma 241 Nevus Anemicus 242 Capillary Malformations 242 Nevus Flammeus (Port-Wine Stain) 242 Nevus Araneus (Spider Angioma) 244 Cutis Marmorata Telangiectatica (van Lohuizen) (Nevus Vascularis Reticularis) 245 Congenital T.