Atlas of Dermatopathology

Günter Burg, MD is Professor of Dermatology and Chairman Emeritus, University of Zurich, Switzerland.Heinz Kutzner, MD is Professor of Dermatology, Institute of Dermatopathology, Friedrichshafen, Germany,Werner Kempf, MD is Professor of Dermatology, Department of Dermatopathology, University of Zurich, Switzerland.Josef Feit, MD is Associate Professor of Pathology, University of Ostrava, Czech Republic.Bruce R. Smoller, MD is Professor and Chairman of the Department of Pathology and Laboratory Medicine, University of Rochester, NY, School of Medicine and Dentistry.

• Preface xvAcknowledgments xvii1 EPIDERMIS 1Nevi 2Epidermal Nevus 2Variant: Inflammatory Linear Verrucous Epidermal Nevus (ILVEN) 3Keratoses 4Seborrheic Keratosis (SK) and Variants 4Variant: Acanthotic Seborrheic Keratosis 4Variant: Reticulated, Pigmented Seborrheic Keratosis 6Variant: Flat Seborrheic Keratosis 6Variant: Papillomatous Seborrheic Keratosis 7Variant: Activated (Irritated) Seborrheic Keratosis 7Variant: Dermatosis Papulosa Nigra 7Variant: Melanoacanthoma (Pigmented Seborrheic Keratosis) 8Variant: Clonal (Intraepidermal) Seborrheic Keratosis (Borst– Jadassohn) 9Variant: Seborrheic Keratosis with Monster Cells (Bowenoid) 10Variant: Hyperkeratotic Seborrheic Keratosis (Stucco Keratosis) 11Confluent and Reticulate Papillomatosis (Gougerot and Carteaud) 12Reticulate Pigmented Anomaly of the Flexures (Dowling–Degos Disease) 13Acanthosis Nigricans 14Solar (Actinic) Keratosis 15Variant: Acantholytic Solar Keratosis 16Variant: Atrophic Solar Keratosis 16Variant: Lichen Planus‐Like Solar Keratosis 17Variant: Hypertrophic (Bowenoid) Solar Keratosis 18Cornu Cutaneum 18Acanthomas, Non‐Viral 19Solar Lentigo 19Callus, Factitial Acanthoma 20Knuckle Pads (Chewing Pads) 21Pale (Clear) Cell Acanthoma 22Large Cell Acanthoma 23Differential Diagnosis: Epidermolytic Acanthoma 24Differential Diagnosis: Congenital Ichthyosiform Erythroderma 25Acantholytic Acanthoma 26Warty Dyskeratoma 27Porokeratoma (Porokeratosis Mibelli) 30Acanthomas, Viral 31Verruca Vulgaris 31Variant: Verruca Plana 33Variant: Condyloma Acuminatum 34Bowenoid Papulosis 35Acrokeratosis Verruciformis (Hopf) 37Molluscum Contagiosum 38“Pseudocarcinomas” and Neoplasms with Intermediate Malignant Potential 40Keratoacanthoma (KA) 40Epithelioma Cuniculatum (Verrucous Carcinoma) (EC/VC) 44Papillomatosis Cutis Carcinoides 45Florid Papillomatosis of the Oral Cavity (Oral Verrucous Carcinoma) 46Buschke–Löwenstein Tumor (Giant Condyloma) 47Malignant Epidermal Neoplasms 48Bowen’s Disease (Carcinoma in situ) 48Variant: Clear Cell Bowen’s Disease 50Variant: Cutaneous Horn (Cornu Cutaneum) on Bowen’s Disease 51Variant: Pigmented (Anogenital) and Clonal Bowen’s Disease 52Variant: Erythroplasia of Queyrat and Vulvar Intraepithelial Neoplasia 53Basal Cell Carcinoma (BCC) 54Variant: Nodular BCC 54Variant: Infundibulocystic BCC 56Variants of BCC With Ductal, Matrical or Sebaceous Differentiation 57Variant: Superficial BCC 60Variant: Pigmented BCC 61Variant: Adenoid‐Cystic BCC 62Variant: Sclerodermiform (Morpheaform) BCC 64Clinical Variants: Ulcerating BCCs 66Histological Variants: Metatypic BCC with Squamoid Differentiation 67Syndromatic BCC (Basal Cell Nevus Syndrome, Gorlin–Goltz) 69Fibroepithelioma of Pinkus 70Squamous Cell Carcinoma (SCC) 72Variant: Well‐Differentiated SCC 72Variant: Acantholytic SCC (Epithelioma Spinocellulare Segregans of Delacretaz) 74Variant: Myxoid SCC 76Variant: Follicular (Infundibular) SCC 77Variant: Spindle Cell (Fusicellular) SCC 78Squamous Cell Carcinomas in Special Sites 792 ADNEXAL 85Sweat Gland Differentiation 86Nevi, Hyperplasias, and Benign Adnexal Neoplasms (BAN) 86Eccrine Differentiation 86Apocrine Differentiation 93Malignant Adnexal Neoplasms 105Eccrine Differentiation 105Apocrine Differentiation 109Sebaceous Differentiation 110Hyperplasias and Hamartomas 111Ectopic (Heterotopic) Sebaceous Glands (Fordyce Glands) 111(Senile) Sebaceous Gland Hyperplasia 112Nevus Sebaceous (Jadassohn) 113Variant: Pilo‐Sebaceous Hamartoma 114Benign Neoplasms 114Sebaceous Adenoma 114Muir–Torre Syndrome 115Sebaceous Epithelioma (Sebaceoma) 116Malignant Neoplasms 118Sebaceous Carcinoma 118Hair Follicle Differentiation 119Nevi, Hyperplasia, and Hamartomas 119Hair Follicle Nevus 119Conical Infundibular Acanthoma (Giant Dilated Pore of Winer) 120Benign Neoplasms 121Pilar Sheath Acanthoma 121Trichilemmoma (Tricholemmoma) 122Tumor of the Follicular Infundibulum (Infundibuloma) 124Trichoepithelioma (Superficial Trichoblastoma) 125Trichoblastoma (Trichoblastic Fibroma; Immature Trichoepithelioma) 127Trichoepithelioma (Sclerosing Epithelial Hamartoma) 131Trichofolliculoma (Folliculosebaceous Cystic Hamartoma) 133Trichoadenoma (Nikolowski) 136Pilomatricoma (Calcifying Epithelioma Malherbe) 137Proliferating Trichilemmal (Pilar) Tumor (PTT) (Proliferating Trichilemmal Cyst) 138Malignant Neoplasms 140Malignant Pilomatricoma (Pilomatrical Carcinoma) 140Trichilemmal Carcinoma 141Trichoblastic Carcinoma 142Pilosebaceous Mesenchyme 143Benign Neoplasm 143Trichodiscoma (Follicular Fibroma, Fibrofolliculoma, Perifollicular Fibroma) 1433 PAGET’S DISEASE 145Mammary Paget’s Disease 146Extramammary Paget’s Disease 1464 MELANOCYTES 149Non‐Neoplastic Hyperpigmentations 150Ephelides (Genuine Freckles) 150PUVA (Psoralen UVA) Lentigo 150“Nevus” Spilus (Speckled Lentiginous Nevus; Café‐Au‐Lait Spot) 151“Ink” Spot Lentigo (Reticulated Melanocytic Macule) 152Senile Freckles (Solar [Actinic] Lentigo) 153Mucosal Lentiginous Spots (Lip, Buccal, and Genital Mucosa) 154Nevi 155Common Acquired Melanocytic Nevi 155Melanosis Neviformis (Pigmented Hairy Epidermal Nevus; Becker Nevus) 155Junctional Nevus 156Compound Nevus 157Dermal Nevus 158Variant: Miescher’s Nevus (Dermal Nevus) 160Variant: Balloon Cell Nevus 161Variant: “Activated” Acral (Lentiginous) Melanocytic Nevus 161Variant: (Atypical) Genital Melanocytic Nevus 162Variant: Halo Nevus (Leukoderma Centrifugum Acquisitum; Sutton Nevus) 163Variant: Eczematoid Melanocytic (Meyerson’s) Nevus 165Variant: Osteo‐Nevus of Nanta 166Variant: Combined Epithelioid Spitzoid Nevus, “Wiesner Nevus” (BAP-1 Deficient Epithelioid Melanocytic Tumor) 167Variant: Recurrent (Persistent) Melanocytic Nevus (Pseudomelanoma) 167Variant: Nevus in Pregnancy 168Variant: Ancient Nevus 170Blue Nevi 171Common Blue Nevus 171Common Blue Nevus 172Dermal Melanocytosis 177Nevus Fuscoceruleus (Ota; Ito; Mongolian Spot) 177Spindle and/or Epithelioid Cell Nevus 178Common Nevus of Spitz 178Variants of Spindle and Epithelioid Cell Nevus 179Variant: Pigmented Spindle Cell Nevus (Reed) 182Benign Melanocytic Lesions with Peculiar Structural Features 183Melanocytic Nevus with Clonal Proliferation 183Atypical (Dysplastic) Melanocytic (Clark’s) Nevus (B‐K Mole Syndrome) 185Congenital Nevi, Small and Medium‐Sized (1.5–20 cm) 186Malignant Melanocytic Neoplasms 188Lentigo Maligna Dubreuilh (Hutchinson’s Freckle) 188Malignant Melanoma 189Variant: Superficial Spreading Melanoma (SSM) 190Variant: Lentigo Maligna Melanoma (LMM) 192Variant: Nodular Melanoma (NM) 193Variant: Acral Lentiginous Melanoma (ALM) 194Variant: Melanoma in Large Congenital Melanocytic Nevus (LCMN) 196Variant: Cutaneous Metastasis of Melanoma 197Special Localisations of Malignant Melanoma 204Tumor Thickness and Levels 205Common Clinical Differential Diagnoses of Malignant Melanoma 2055 CONNECTIVE TISSUE 207Nevi 208Connective Tissue Nevus (Shagreen Patch; Cobblestone Nevus; Nevus Collagenicus) 208Fibrous Neoplasms 209Soft Fibroma (Skin Tag; Acrochordon) 209Perifollicular Fibroma (Fibrofolliculoma; Trichodiscoma) 210Variant: Sclerotic Fibroma (Plywood Fibroma; Storiform Collagenoma) 211Variant: Fibrous Papule of the Nose 212Variant: Pleomorphic Sclerosing Fibroma with Multinucleated Cells 212Keloid 213Infantile Digital Fibromatosis (Inclusion Body Fibromatosis; Recurring Digital Fibrous Tumor of Children; Reye’s Tumor) 214Malformations with Supernumerary Tissue Elements 216Supernumerary Digit (Rudimentary Digit; Rudimentary Polydactyly) 216Differential Diagnosis: Acral Acquired Fibrokeratoma 216Accessory Tragus (Preauricular Tag) 217Accessory Nipple (Ectopic Breast; Polythelia) 218Fibrohistiocytic Neoplasms 218Dermatofibroma (Benign Fibrous Histiocytoma; Fibroma Durum; Sclerosing Hemangioma) 218Dermatofibrosarcoma Protuberans 227Variant: Pigmented Dermatofibrosarcoma Protuberans (Bednar’s Tumor) 230Variant: Giant Cell Fibroblastoma 231Pleomorphic Dermal Sarcoma (PDS) 231Miscellaneous Tumors 234Epithelioid Sarcoma 234Dermatomyofibroma 2366 VESSELS 239Hamartomas, Nevi, and Malformations 240Phacomatosis Pigmentovascularis 240Eccrine Angiomatous Hamartoma 241Nevus Anemicus 242Capillary Malformations 242Nevus Flammeus (Port-Wine Stain) 242Nevus Araneus (Spider Angioma) 244Cutis Marmorata Telangiectatica (van Lohuizen) (Nevus Vascularis Reticularis) 245Congenital Telangiectatic Erythema (Bloom’s Syndrome) 247Venous Malformations 248Blue Rubber Bleb Nevus Syndrome (Familial Venous Malformation) 248Hereditary Hemorrhagic Telangiectasia (Osler–Weber–Rendu) 249Angioma Serpiginosum 250Venular Aneurysm (Venous Lake) 251Cavernous Hemangioma (in Maffucci Syndrome) 252Sinusoidal Hemangioma 253Spindle Cell Hemangioma (Formerly Spindle Cell Hemangioendothelioma) 254Arteriovenous Malformations 256Acral Arteriovenous Hemangioma (Cirsoid Aneurysm) 256Glomuvenular Malformation (“Glomangioma”) 257Lymphatic Malformations 259Superficial Lymphatic Malformation (Superficial Lymphangioma) 259Cystic Lymphatic Malformation (Cystic Hygroma) 260Targetoid Hemosiderotic (Hobnail) Hemangioma 261Progressive Lymphangioma (Benign Lymphangioendothelioma) 262Lymphangiomatosis 263Angiokeratomas 264Verrucous Hemangioma (Venous Malformation) 265Variant: Solitary Angiokeratoma 268Variant: Angiokeratoma Circumscriptum Naeviformis 269Variant: Fordyce Angiokeratoma 269Variant: Angiokeratoma Acroasphycticum Digitorum (Mibelli) 269Variant: Multiple “Pinpoint” Angiokeratomas (Angiokeratoma Corporis Diffusum; Fabry’s Disease) 269Variant: Acral Pseudolymphomatous Angiokeratoma of Children (APACHE) 269Hyperplasias 270Granuloma Pyogenicum (Lobular Capillary Hemangioma; Botryomykoma) 270Differential Diagnosis: Pyogenic Granuloma‐Like Granulation Tissue 272Bacillary Angiomatosis 273Verruga Peruana 274Intravascular Papillary Endothelial Hyperplasia (Masson) 275Acroangiodermatitis Mali (Pseudo‑Kaposi’s Sarcoma) 276Benign Vascular Neoplasms 278Epithelioid Hemangioma (Angiolymphoid Hyperplasia with Eosinophilia, ALHE) 278Endothelial Differentiation 280Infantile Capillary and Congenital Hemangioma 280Cherry Angioma (Senile Hemangioma) 281Microvenular (Microcapillary) Hemangioma 282Tufted Angioma 283Kaposiform Hemangioendothelioma 285Glomeruloid Hemangioma in POEMS Syndrome 287Pericytic Differentiation 288 Imitator: Solitary Fibrous Tumor of the Skin (SFT) 289Myopericytoma (Infantile Myofibromatosis; Perivascular Myoma (incl. Myofibroma)) 290Glomoid and Myoid Differentiation 292Glomus Tumor 292Angioleiomyoma (Angiomyoma; Vascular Leiomyoma) 294Recently Described Benign Vascular Tumors 296Symplastic Hemangioma 296Papillary Hemangioma 297Vascular Neoplasms of Intermediate Malignant Potential 298Kaposi’s Sarcoma (KS) 298Retiform Hemangioendothelioma 305Composite Hemangioendothelioma 306Papillary Intralymphatic Angioendothelioma (PILA) (Malignant Endovascular Papillary Angioendothelioma (Dabska Tumor); Endovascular Papillary Hemangioendothelioma) 306Radiation‐Induced Atypical Vascular Lesion (AVL) (Benign Lymphangiomatous Papule (BLAP)) 308Vascular Neoplasms with High Malignant Potential 309Cutaneous Angiosarcoma 309Radiation‐Induced (Postradiation) Angiosarcoma 312Epithelioid Hemangioendothelioma 312Epithelioid Angiosarcoma 315Differential Diagnosis: Acantholytic (Angiosarcoma‐Like) Squamous Cell Carcinoma 316Glomangiosarcoma (Malignant Glomus Tumor) 317Other Neoplasms with Significant Vascular Component 318Multinucleate Angiohistiocytoma 318Angiofibroma (Adenoma Sebaceum Associated with Pringle–Bourneville Disease) 319Angiolipoma 321Angiolipoleiomyoma (Angiomyolipoma) 322Angiomyxoma 322Intralymphatic Histiocytosis 324Kimura’s Disease 3257 FAT 327Nevus (Hamartoma) 328Nevus Lipomatosus Superficialis Hoffmann Zurhelle 328Neoplasms of Fat Tissue 329Benign Neoplasms 329Common Lipoma and Lipomatosis 329Angiolipoma (see Vessels, Chapter 6) 330Angiomyolipoma (see Vessels, Chapter 6) 330Spindle Cell Lipoma 330Pleomorphic Lipoma (see Pleomorphic Liposarcoma) 332Hibernoma 332Malignant Neoplasms 333Cutaneous Liposarcoma 3338 MUSCLE 337Benign Neoplasms 338Piloleiomyoma (Pilar Leiomyoma) 338Angioleiomyoma (see Vessels, Chapter 6) 340Rhabdomyoma, Adult Type 340Malignant Neoplasms 341Rhabdomyosarcoma 341Superficial Leiomyosarcoma 3429 NERVES 345Benign Neoplasms 346Schwannoma (Neurilemmoma) 349Solitary Neuroma (“Palisaded Encapsulated Neuroma”) 352Variant: Traumatic Neuroma 353Granular Cell Tumor (Abrikossoff) 354Dermal Nerve Sheath Myxoma (Myxoid Neurothekeoma) 356Variant: Cellular Neurothekeoma 357Pacinian Neurofibroma (Pacinoma) 358Malignant Neoplasms 358Malignant Peripheral Nerve Sheath Tumor (Malignant Schwannoma) 358Malignant Granular Cell Tumor 360Neuroendocrine Neoplasm 360Primary Neuroendocrine (Merkel Cell, Trabecular) Carcinoma of the Skin 36010 MAST CELLS 363Solitary Cutaneous Mast Cell Proliferation 364Cutaneous Mastocytoma 364Diffuse Cutaneous Mast Cell Proliferations 365Urticaria Pigmentosa (Juvenile Maculopapular Mastocytosis) 365Telangiectasia Macularis Eruptiva Perstans (Adults) 365Systemic Mast Cell Proliferation 367Involvement of Skin and Bone Marrow 36711 HISTIOCYTES 369Langerhans Cell Histiocytoses (LCH) 370Precursors of Langerhans Cell Histiocytoses 370Congenital Self‐healing Reticulohistiocytosis (Hashimoto–Pritzker) 370Indeterminate Cell Histiocytosis 371Langerhans Cell Histiocytoses (Histiocytosis X) 371Congenital Langerhans Cell Histiocytosis (Letterer–Siwe Disease) 372Hand–Schüller–Christian Adult LHC Histiocytosis 374Solitary Langerhans Cell Tumor (Eosinophilic Granuloma) 375Non‐Langerhans Cell Histiocytoses 376Proliferative 376Proliferative Histiocytoma (Progressive Nodular Histiocytosis, PNH) 376Benign Cephalic Histiocytosis 377Multicentric Reticulohistiocytosis (Lipoid Dermatoarthritis) (Solitary Reticulohistiocytoma) 378Sinus Histiocytosis With Massive Lymphadenopathy 379Granulomatous Storing 380Juvenile Xanthogranuloma (Nevoxanthoendothelioma; Xanthoma Multiplex; Juvenile Giant Cell Granuloma) 380Xanthelasma Palpebrarum 383Verruciform Xanthoma 384Necrobiotic Xanthogranuloma (with Paraproteinemia) 385Hereditary Progressive Mucinous Histiocytosis 386Hemophagocytic 387Familial Hemophagocytic Lymphohistiocytosis 387Histiocytic Cytophagic Panniculitis 38812 HEMATOPOIETIC DISORDERS 389Lymphoid Skin Infiltrates 389Cytomorphology, Major Cell Types 390T‐Cells 390B‐Cells 391Pattern of Small Cell Lymphocytic Infiltrates 392T‐Cell Pattern 392B‐Cell Pattern 392Pseudolymphoma (PL) 393Nodular B‐Cell PL 393Lymphadenosis Cutis Benigna (Lymphocytoma Cutis) 393Differentiation between B‑Pseudolymphoma (PL) and Cutaneous B‐Cell Lymphoma (CBCL) 395Nodular T‐Cell PL 396CD30+ Pseudolymphoma in Scabies 396Papular (Secondary) Syphilis 398Pseudo‐Mycosis Fungoides (Mycosis Fungoides Simulators) 399Lymphomatoid Contact Dermatitis 399Lichen Planus 399Drug Reactions 400Early Vitiligo 400Lichen Sclerosus et Atrophicus 400Pityriasis Lichenoides Chronica 401Graft Versus Host Reaction (Acute) 401Pityriasis Lichenoides et Varioliformis Acuta (PLEVA) 402Pigmented Purpuric Dermatitis (Lichen Aureus) 403Lymphocytic Infiltration Jessner–Kanof 404Cutaneous Mature T‐Cell Lymphoid Neoplasms (CTCL) 405Mycosis Fungoides, Classic Alibert–Bazin Type 405Mycosis Fungoides Patch Stage I 405Mycosis Fungoides Plaque Stage II (CD4+; CD8−) 407Variant: CD8+ Mycosis Fungoides 409Mycosis Fungoides Tumor Stage III 409Large Cell Transformation 410Simulators and Variants of Mycosis Fungoides: “Parapsoriasis” 411Simulator: Small Plaque Parapsoriasis (SPP) (Brocq’s Disease, Digitate Dermatosis) 411Large Plaque Parapsoriasis (LPP) 412Pigmented Purpuric Mycosis Fungoides 412Erythrodermic Mycosis Fungoides 412Folliculotropic (Pilotropic) Mycosis Fungoides 413Syringotropic Mycosis Fungoides (Syringolymphoid Hyperplasia with Alopecia) 414Granulomatous Mycosis Fungoides 415Granulomatous Slack Skin 415Pagetoid Reticulosis (PR), Unilesional (Woringer–Kolopp) 417Sézary Syndrome (SS) 418Variant: Sézary Syndrome, Large Cell Transformation 420CD30‐Positive Lymphoproliferative Disorders (LPD) of the Skin 423Anaplastic Large Cell Lymphoma (ALCL) 424Neutrophil‐Rich (Pyogenic) Anaplastic Large Cell Lymphoma 426Lymphomatoid Papulosis 427Differential Diagnosis: Hodgkin’s Lymphoma, Lymphocyte Predominance 429Subcutaneous Panniculitis‐Like Lymphoma 431Subcutaneous (Panniculitis-Like; Alpha/Beta) T‐Cell Lymphoma 431Differential Diagnosis: Subcutaneous (Panniculitis‐Like) Gamma/Delta lymphoma 432Differential Diagnosis: Lupus Panniculitis (Lupus Profundus) 433Primary Cutaneous Peripheral Lymphoma (PTL), Unspecified (NOS) 434Primary Cutaneous CD4‐positive (Acral) Small/Medium‐Sized T‐Cell Lymphoproliferative Disorder 435Cutaneous Aggressive Epidermotropic CD8‐positive T‐Cell Lymphoma (Berti) 436Differential Diagnosis: Febrile Ulceronecrotic PLEVA (Mucha–Habermann Disease) 437Extranodal NK/T‐Cell Lymphoma, Nasal Type (Subcutaneous) 439Hydroa Vacciniforme‐Like Lymphoma 440Angioimmunoblastic T‐Cell Lymphoma 441Cutaneous Mature B‐Cell Lymphoid Neoplasms (CBCL) 443Cutaneous Marginal Zone B‐Cell Lymphoma (MZL; MALT Type) 444Variant: Immunocytoma 447Differential Diagnoses: Multiple Myeloma/Plasmacytoma 448Primary Cutaneous Follicle Center Lymphoma (FCL) 449Diffuse Large B‐Cell Lymphoma (DLBCL) 451Variant: Cutaneous Diffuse Large B‐Cell Lymphoma (Leg Type) 451Variant: T‐Cell‐Rich B‐Cell Lymphoma (DLBCL) 454Cutaneous Spindle B‐Cell Lymphoma 455Extracutaneous B‐Cell Lymphoma (BCL) with Frequent Skin Involvement 457Mantle Cell Lymphoma 457Burkitt’s Lymphoma (BL) 458Lymphomatoid Granulomatosis (Liebow) (LYG) 460Intravascular Lymphomas 461Intravascular Large B‐Cell Lymphoma (IV‐LBCL) (Systemic Angioendotheliomatosis) 461Intravascular T Cell Lymphoma 462Secondary Skin Involvement in Leukemias/Lymphomas 463Chronic Lymphocytic Leukemia (CLL) 463Myeloid and Monocytic Leukemias 464T‐Zone Lymphoma 466Adult T‐Cell Leukemia/ Lymphoma (ATLL) 467Immature Hematopoietic Malignancies 468Blastic Plasmacytoid Dendritic Cell Neoplasm 468Precursor Lymphoblastic Leukemia/Lymphoma 47013 CUTANEOUS CYSTS 471Cysts with Epithelial Lining 472Stratified Squamous Epithelium 472Epidermal (Infundibular) Cysts 472Variant: Epidermal Proliferating Cyst 473Variant: Epidermal Cyst with Pigment and Vellus Hairs 473Vellus Hair Cyst 474Trichilemmal (Isthmus‐Catagen) Cyst 475Milia 476Follicular Hybrid Cyst 477Hidrocystoma (Cystadenoma) 478Steatocystoma, Multiplex and Simplex 481Dermoid Cyst 482Pilonidal Sinus (Pilonidal Cyst) 484Non‐Stratified Squamous Epithelium 485Cutaneous Ciliated Cyst of the Lower Limb 485Median Raphe Cyst 486Cysts without Epithelial Lining (Pseudocysts) 487Oral Mucous Cyst and Superficial Mucocele of the Lip 487Digital Myxoid Cyst 488Synovial Cyst (Ganglion) 490Index 491