Soft Tissue Tumors of the Skin (eBook)

Steven D. Billings, MDProfessor of PathologyCleveland Clinic Lerner College of MedicineCleveland, OH, USARajiv M. Patel, MDProfessor of Pathology and DermatologyUniversity of Michigan Medical SchoolAnn Arbor, MI, USADarya Buehler, MDAssistant ProfessorUniversity of Wisconsin School of Medicine and Public HealthPathology and Laboratory MedicineMadison, WI, USA

Preface 5
Acknowledgment 6
Contents 7
Contributors 9
1: Introduction and General Approach 10
Selected References 23
2: Ancillary Diagnostic Tests in the Diagnosis of Cutaneous Soft Tissue Neoplasms 24
Basic Principles of Diagnostic Immunohistochemistry 24
Attention to Positive and Negative Internal Controls 24
Evaluation of all Pieces of Tissue on the Entire Slide and Careful Discrimination of Neoplastic from Nonneoplastic Cell Populations 26
The Use of a Panel of Immunostains, Including Both Expected Positives and Negatives for All of the Entities in the Histologic Differential Diagnosis 26
Epithelial Markers 26
Keratins 26
Epithelial Membrane Antigen (EMA) 28
p63 and p40 28
Nerve Sheath Markers 28
S100 Protein 28
SOX10 29
Claudin-1 29
GLUT-1 29
Melanocyte Specific Markers 29
HMB-45 29
Melan-A 31
Tyrosinase 31
Microphthalmia Transcription Factor 31
Markers of Smooth and Skeletal Muscle 31
Desmin 31
Smooth Muscle Actin 31
MyoD1 and Myogenin 33
H-Caldesmon 33
Endothelial Markers 33
CD31 33
CD34 34
Podoplanin (D2-40) 34
FLI1 and ERG 35
vWF (Factor VIII) 37
Histiocytic Markers (CD68, CD163, CD11c, CD4) 37
ALK 37
Markers that Are Generally of Little Value 37
Vimentin 37
PGP9.5 39
Putative Markers of Atypical Fibroxanthoma and/or Superficial Undifferentiated Pleomorphic Sarcoma (CD99, CD10, Procollagen, CD34) 40
Applications of Immunohistochemistry and Fluorescence In Situ Hybridization in Various Differential Diagnoses in Cutaneous Soft Tissue Pathology 40
IHC in the Evaluation of Cutaneous Pleomorphic Spindle Cell Tumors 40
Leiomyosarcoma 42
Atypical Fibroxanthoma/Superficial Undifferentiated Pleomorphic Sarcoma (AFX/SUPS) 43
Other Rare Pleomorphic Spindle Cell Sarcomas that May Involve the Skin 46
IHC in the Differential Diagnosis of “Monomorphic” Spindle Cell Cutaneous Tumors 46
DFSP, CFH, and Related Lesions 46
LGFMS and Perineurioma 48
IHC in the Differential Diagnosis of Epithelioid Malignant Cutaneous Tumors 48
Epithelioid Sarcoma and Epithelioid Endothelial Tumors 48
Melanoma 51
Myoepithelial Tumors 53
IHC in the Differential Diagnosis of Tumors Composed of Small, Round Cells 55
Comments on Specific Round Cell Tumors 56
Other Application of IHC in Cutaneous Mesenchymal Tumors 60
Adipocytic Tumors 60
Atypical Vascular Lesions and Angiosarcomas Arising After Therapeutic Irradiation 62
Selected References 63
3: Mimics of Cutaneous Mesenchymal Tumors 66
Palisading Necrobiotic Granulomas: Granuloma Annulare and Rheumatoid Nodule 66
Clinical Features 66
Pathologic Features 66
Differential Diagnosis 69
Non-mesenchymal Spindle Cell Neoplasms that Mimic Primary Cutaneous Soft Tissue Lesions 70
Sarcomatoid Carcinoma 70
Clinical Features 70
Pathologic Features 71
Differential Diagnosis 73
Spindle Cell, Desmoplastic, and Dedifferentiated Melanoma 74
Clinical Features 74
Pathologic Features 75
Differential Diagnosis 76
Cellular Blue Nevus 79
Clinical Features 79
Pathologic Features 79
Differential Diagnosis 79
Massive Localized Lymphedema 80
Clinical Features 80
Pathologic Features 81
Differential Diagnosis 82
Silicone Granuloma 83
Clinical Features 83
Pathologic Features 84
Differential Diagnosis 85
Mycobacterial Spindle Cell Pseudotumor 86
Clinical Features 86
Pathologic Features 86
Differential Diagnosis 87
Acroangiodermatitis 89
Clinical Features 89
Pathologic Features 89
Differential Diagnosis 89
Bizarre Parosteal Osteochondromatous Proliferation (BPOP, Nora Lesion) 89
Clinical Features 89
Pathologic Features 90
Differential Diagnosis 92
Crystal-Storing Histiocytosis 92
Clinical Features 92
Pathologic Features 92
Differential Diagnosis 93
Erythema Elevatum Diutinum 94
Clinical Features 94
Pathologic Features 94
Differential Diagnosis 95
Metastatic Clear Cell Renal Cell Carcinoma 96
Clinical Features 96
Pathologic Features 96
Differential Diagnosis 96
Selected References 98
4: Benign Fibrous, Fibrohistiocytic, and Myofibroblastic Lesions 100
Keloid 100
Clinical Features 100
Pathologic Features 100
Differential Diagnosis 101
Fibrous Papule (Angiofibroma) 101
Clinical Features 101
Pathologic Features 102
Differential Diagnosis 102
Acquired Digital Fibrokeratoma 102
Clinical Features 102
Pathologic Features 106
Differential Diagnosis 106
Angiofibroma of Soft Tissue 106
Clinical Features 106
Pathologic Features 106
Differential Diagnosis 106
Pleomorphic Fibroma of the Skin 108
Clinical Features 108
Pathologic Features 108
Differential Diagnosis 109
Gardner-Associated Fibroma 109
Clinical Features 109
Pathologic Features 110
Differential Diagnosis 110
Nuchal Fibroma 112
Clinical Features 112
Pathologic Features 112
Differential Diagnosis 113
Calcifying Aponeurotic Fibroma 113
Clinical Features 113
Pathologic Features 113
Differential Diagnosis 113
Elastofibroma 115
Clinical Features 115
Pathologic Features 115
Differential Diagnosis 115
Desmoplastic Fibroblastoma (Collagenous Fibroma) 115
Clinical Features 115
Pathologic Features 115
Differential Diagnosis 116
Sclerotic Fibroma (Storiform Collagenoma) 118
Clinical Features 118
Pathologic Features 118
Differential Diagnosis 118
Fibrous Hamartoma of Infancy 118
Clinical Features 118
Pathologic Features 118
Differential Diagnosis 121
Infantile Digital Fibroma (Inclusion Body Fibromatosis) 122
Clinical Features 122
Pathologic Features 122
Differential Diagnosis 124
Plaque-Like CD34-Positive Dermal Fibroma 124
Clinical Features 124
Pathologic Features 124
Differential Diagnosis 124
Dermatomyofibroma 126
Clinical Features 126
Pathologic Features 126
Differential Diagnosis 126
Fibroblastic Connective Tissue Nevus 127
Clinical Features 127
Pathologic Features 127
Differential Diagnosis 128
Superficial Fibromatoses 129
Clinical Features 129
Pathologic Features 129
Differential Diagnosis 132
Juvenile Hyaline Fibromatosis 133
Clinical Features 133
Pathologic Features 133
Differential Diagnosis 133
Infantile Fibromatosis (Lipofibromatosis) 135
Clinical Features 135
Pathologic Features 135
Differential Diagnosis 135
Benign Fibrous Histiocytoma (Dermatofibroma) 137
Clinical Features 137
Pathologic Features 137
Conventional Benign Fibrous Histiocytoma/Dermatofibroma 143
Lipidized (Ankle-Type) Fibrous Histiocytoma 143
Cellular Fibrous Histiocytoma 143
Aneurysmal and/or Hemosiderotic Fibrous Histiocytoma 143
Atypical Fibrous Histiocytoma/Dermatofibroma with Monster Cells 143
Deep Fibrous Histiocytoma 143
Rare Variants 143
Differential Diagnosis 145
Multinucleate Cell Angiohistiocytoma 145
Clinical Features 145
Pathologic Features 146
Differential Diagnosis 147
Epithelioid Fibrous Histiocytoma 147
Clinical Features 147
Pathologic Features 147
Differential Diagnosis 149
Juvenile (Solitary) Xanthogranuloma 149
Clinical Features 149
Pathologic Features 149
Differential Diagnosis 151
Solitary Reticulohistiocytoma/Multicentric Reticulohistiocytosis 151
Clinical Features 151
Pathologic Features 151
Differential Diagnosis 151
Xanthomas 152
Clinical Features 152
Pathologic Features 153
Differential Diagnosis 153
Tenosynovial Giant Cell Tumor 154
Clinical Features 154
Pathologic Features 154
Differential Diagnosis 154
Superficial Acral Fibromyxoma (Digital Fibromyxoma) and Cellular Digital Fibroma 156
Clinical Features 156
Pathologic Features 156
Differential Diagnosis 156
Cutaneous Myxoma/Superficial Angiomyxoma 158
Clinical Features 158
Pathologic Features 158
Differential Diagnosis 158
Cellular Neurothekeoma 160
Clinical Features 160
Pathologic Features 160
Differential Diagnosis 160
Nodular Fasciitis 163
Clinical Features 163
Pathologic Features 163
Differential Diagnosis 163
Proliferative Fasciitis 167
Clinical Features 167
Pathologic Features 168
Differential Diagnosis 169
Ischemic Fasciitis 169
Clinical Features 169
Pathologic Features 169
Differential Diagnosis 171
Fibroma of Tendon Sheath 171
Clinical Features 171
Pathologic Features 171
Differential Diagnosis 171
Calcifying Fibrous Pseudotumor 174
Clinical Features 174
Pathologic Features 174
Differential Diagnosis 174
Fibroosseous Pseudotumor of Digits 175
Clinical Features 175
Pathologic Features 175
Differential Diagnosis 177
Selected References 177
5: Fibrous, Fibrohistiocytic, and Myofibroblastic Tumors of Intermediate Malignancy 184
Dermatofibrosarcoma Protuberans 184
Clinical Features 184
Pathologic Features 185
Pigmented Variant (Bednar Tumor) 185
Giant Cell Fibroblastoma 185
Myxoid DFSP 186
Atrophic Variant 189
Sclerosing Variant 189
Myoid Variant 189
Granular Cell Variant 190
DFSP with Fibrosarcomatous Transformation 190
Differential Diagnosis 191
Plexiform Fibrohistiocytic Tumor 197
Clinical Features 197
Pathologic Features 197
Differential Diagnosis 197
Angiomatoid Fibrous Histiocytoma 200
Clinical Features 200
Pathologic Features 200
Differential Diagnosis 203
Giant Cell Tumor of Soft Tissue 204
Clinical Features 204
Pathologic Features 205
Differential Diagnosis 206
Superficial CD34-Positive Fibroblastic Tumor 206
Clinical Features 206
Pathologic Features 207
Differential Diagnosis 209
Inflammatory Myofibrolastic Tumor 209
Clinical Features 209
Pathologic Features 209
Differential Diagnosis 211
Selected References 212
6: Malignant Fibrous, Fibrohistiocytic, and Myofibroblastic Tumors 214
Congenital/Infantile Fibrosarcoma 214
Clinical Features 214
Pathologic Features 214
Differential Diagnosis 216
Adult-Type Fibrosarcoma 216
Clinical Features 216
Pathologic Features 217
Differential Diagnosis 218
Low-Grade Fibromyxoid Sarcoma 218
Clinical Features 218
Pathologic Features 218
Differential Diagnosis 220
Sclerosing Epithelioid Fibrosarcoma 221
Clinical Features 221
Pathologic Features 221
Differential Diagnosis 222
Myxofibrosarcoma 223
Clinical Features 223
Pathologic Features 223
Differential Diagnosis 227
Undifferentiated Pleomorphic Sarcoma 227
Clinical Features 227
Pathologic Features 227
Differential Diagnosis 228
Low-Grade Myofibroblastic Sarcoma (Myofibrosarcoma) 229
Clinical Features 229
Pathologic Features 229
Differential Diagnosis 230
Myxoinflammatory Fibroblastic Sarcoma 231
Clinical Features 231
Pathologic Features 231
Differential Diagnosis 231
Atypical Fibroxanthoma and Pleomorphic Dermal Sarcoma 234
Clinical Features 234
Pathologic Features 234
Differential Diagnosis 239
Selected References 240
7: Cutaneous Vascular Lesions 243
Benign Vascular Proliferations of the Skin 243
Capillary Hemangioma (Cherry Hemangioma or Campbell De Morgan Spot) 243
Clinical Features 243
Pathologic Features 244
Differential Diagnosis 244
Pyogenic Granuloma 244
Clinical Features 244
Pathologic Features 245
Differential Diagnosis 245
Infantile Hemangioma 245
Clinical Features 245
Pathologic Features 247
Differential Diagnosis 250
Congenital Nonprogressive Hemangioma 251
Clinical Features 251
Pathologic Features 251
Differential Diagnosis 251
Venous Malformation (So-Called Cavernous/Sinusoidal Hemangioma) 253
Clinical Features 253
Pathologic Features 254
Differential Diagnosis 255
Hyperkeratotic Vascular Lesions: 256
Angiokeratoma 256
Clinical Features 256
Pathologic Features 257
Differential Diagnosis 257
Verrucous Venulocapillary Malformation (Verrucous Hemangioma) 258
Clinical Features 258
Pathologic Features 258
Differential Diagnosis 258
Arteriovenous Hemangioma (Acral Arteriovenous Tumor) and Arteriovenous Malformations 260
Clinical Features 260
Pathologic Features 260
Differential Diagnosis 261
Venous Lake 261
Clinical Features 261
Pathologic Features 261
Differential Diagnosis 261
Acquired Elastotic Hemangioma 261
Pathologic Features 262
Differential Diagnosis 263
Microvenular Hemangioma 264
Clinical Features 264
Pathologic Features 264
Differential Diagnosis 264
Hobnail Lymphatic Malformation (Hobnail Hemangioma, Targetoid Hemosiderotic Lymphatic Malformation, Targetoid Hemosiderotic Hemangioma) 264
Clinical Features 264
Pathologic Features 266
Differential Diagnosis 266
Tufted Angioma 267
Clinical Features 267
Pathologic Features 267
Differential Diagnosis 267
Spindle Cell Hemangioma 269
Clinical Features 269
Pathologic Features 269
Differential Diagnosis 270
Epithelioid Hemangioma (Angiolymphoid Hyperplasia with Eosinophilia) 271
Clinical Features 271
Pathologic Features 271
Differential Diagnosis 273
Cutaneous Epithelioid Angiomatous Nodule 275
Clinical Features 275
Pathologic Features 275
Differential Diagnosis 275
Cutaneous Lymphatic Malformation (Lymphangioma Circumscriptum) 275
Clinical Features 275
Pathologic Features 275
Differential Diagnosis 278
Acquired Progressive Lymphangioma (“Benign Angioendothelioma”) 278
Clinical Features 278
Pathologic Features 278
Differential Diagnosis 279
Papillary Hemangioma 280
Clinical Features 280
Pathologic Features 280
Differential Diagnosis 280
Reactive Vascular Lesions 282
Intravascular Papillary Endothelial Hyperplasia (Masson Tumor) 282
Clinical Features 282
Pathologic Features 282
Differential Diagnosis 282
Reactive Angioendotheliomatosis 284
Clinical Features 284
Pathologic Features 284
Differential Diagnosis 284
Glomeruloid Hemangioma 284
Clinical Features 284
Pathologic Features 284
Differential Diagnosis 284
Bacillary Angiomatosis 287
Clinical Features 287
Pathologic Features 287
Differential Diagnosis 287
Kaposi Sarcoma 287
Clinical Features 287
Pathologic Features 288
Differential Diagnosis 290
Vascular Tumors of Intermediate Malignancy 292
Kaposiform Hemangioendothelioma 292
Clinical Features 292
Pathologic Features 293
Differential Diagnosis 295
Hobnail Hemangioendotheliomas 295
Clinical Features 295
Pathologic Features 296
Differential Diagnosis 296
Composite Hemangioendothelioma 298
Clinical Features 298
Pathologic Features 298
Differential Diagnosis 298
Pseudomyogenic (Epithelioid Sarcoma-Like) Hemangioendothelioma 301
Clinical Features 301
Pathologic Features 301
Differential Diagnosis 301
Malignant Vascular Tumors 303
Epithelioid Hemangioendothelioma 303
Clinical Features 303
Pathologic Features 303
Differential Diagnosis 305
Angiosarcoma 305
Clinical Features 305
Pathologic Features 305
Differential Diagnosis 306
Radiation- and Lymphedema-Associated Vascular Tumors 309
Angiosarcoma 309
Clinical Features 309
Pathologic Features 309
Differential Diagnosis 309
Radiation-Induced Atypical Vascular Lesion 309
Clinical Features 309
Pathologic Features 311
Differential Diagnosis 311
Selected References 312
8: Perivascular Tumors 315
Angioleiomyoma 315
Clinical Features 315
Pathologic Features 315
Differential Diagnosis 316
Glomus Tumor 316
Clinical Features 316
Pathologic Features 318
Differential Diagnosis 318
Glomuvenous Malformation 318
Clinical Features 318
Pathologic Features 319
Differential Diagnosis 319
Glomangiomyoma 319
Clinical Features 319
Pathologic Features 319
Differential Diagnosis 320
Myopericytoma 321
Clinical Features 321
Pathologic Features 321
Differential Diagnosis 323
Myofibroma 324
Clinical Features 324
Pathologic Features 324
Differential Diagnosis 324
Malignant Glomus Tumor and Glomus Tumor of Uncertain Malignant Potential 324
Clinical Features 324
Pathologic Features 326
Differential Diagnosis 328
Selected References 328
9: Adipocytic Tumors 330
Lipoma 330
Clinical Features 330
Pathologic Features 330
Differential Diagnosis 332
Angiolipoma 333
Clinical Features 333
Pathologic Features 333
Differential Diagnosis 333
Spindle Cell Lipoma and Pleomorphic Lipoma 333
Clinical Features 333
Pathologic Features 334
Differential Diagnosis 337
Chondroid Lipoma 338
Clinical Features 338
Pathologic Features 338
Differential Diagnosis 339
Hibernoma 339
Clinical Features 339
Pathologic Features 339
Differential Diagnosis 339
Lipoblastoma 340
Clinical Features 340
Pathologic Features 340
Differential Diagnosis 340
Nevus Lipomatosus 342
Clinical Features 342
Pathologic Features 342
Differential Diagnosis 342
Pleomorphic Liposarcoma 342
Clinical Features 342
Pathologic Features 342
Differential Diagnosis 342
Atypical Lipomatous Tumor 345
Clinical Features 345
Pathologic Features 345
Differential Diagnosis 345
Dedifferentiated Liposarcoma 347
Clinical Features 347
Pathologic Features 347
Differential Diagnosis 347
Myxoid Liposarcoma 348
Clinical Features 348
Pathologic Features 348
Differential Diagnosis 350
Selected References 350
10: Nerve Sheath and Related Tumors 352
Neurofibroma 352
Clinical Features 352
Pathologic Features 352
Differential Diagnosis 354
Schwannoma 356
Clinical Features 356
Pathologic Features 356
Cellular Schwannoma 357
Plexiform Schwannoma 358
Microcystic/Reticular Schwannoma 359
Epithelioid Schwannoma 360
Neuroblastoma-Like Schwannoma 361
Pseudoglandular Schwannoma and Schwannomas with True Glands 361
Schwannoma with Secondary Malignancy 361
Differential Diagnosis 362
Perineurioma 364
Clinical Features 364
Pathologic Features 365
Differential Diagnosis 367
Hybrid Schwannoma/Perineurioma 368
Clinical Features 368
Pathologic Features 369
Differential Diagnosis 369
Granular Cell Tumor 370
Clinical Features 370
Pathologic Features 371
Differential Diagnosis 373
Atypical and Malignant Granular Cell Tumor 374
Clinical Features 374
Pathologic Features 374
Differential Diagnosis 374
Dermal Nerve Sheath Myxoma 375
Clinical Features 375
Pathologic Features 376
Differential Diagnosis 376
Solitary Circumscribed Neuroma (Palisaded Encapsulated Neuroma) 377
Clinical Features 377
Pathologic Features 378
Differential Diagnosis 379
Other Neuromas 379
Traumatic Neuroma 379
Morton Neuroma 379
Pacinian Neuroma 379
Rudimentary Polydactyly (Supernumerary Digit) 379
Meningioma 381
Clinical Features 381
Pathologic Features 381
Differential Diagnosis 381
Malignant Peripheral Nerve Sheath Tumor (MPNST) 382
Clinical Features 382
Pathologic Features 383
Differential Diagnosis 383
Ewing Sarcoma 384
Clinical Features 384
Pathologic Features 385
Differential Diagnosis 387
Selected References 387
11: Genital Mesenchymal Tumors 389
Genital Stromal Tumors 389
Fibroepithelial Stromal Polyp 389
Clinical Features 389
Pathologic Features 390
Differential Diagnosis 390
Cellular Angiofibroma (Angiomyofibroblastoma-Like Tumor of the Male Genital Tract) 390
Clinical Features 390
Pathologic Features 393
Differential Diagnosis 394
Mammary-Type Myofibroblastoma 395
Clinical Features 395
Pathologic Features 396
Differential Diagnosis 396
Angiomyofibroblastoma 398
Clinical Features 398
Pathologic Features 398
Differential Diagnosis 398
Deep Angiomyxoma 398
Clinical Features 398
Pathologic Features 399
Differential Diagnosis 399
Ancillary Studies for Genital Stromal Tumors 400
Immunohistochemistry 400
Genetics 400
RB1/13q14 400
HMGA2/12q14.3 401
Prepubertal Vulval Fibroma 402
Clinical Features 402
Pathologic Features 402
Differential Diagnosis 402
Massive Vulval Edema 403
Clinical Features 403
Pathologic Features 403
Differential Diagnosis 403
Smooth Muscle Tumors of the External Genitalia 404
Clinical Features 404
Pathologic Features 404
Differential Diagnosis 405
Selected References 408
12: Soft Tissue Tumors of Uncertain Histogenesis 410
Epithelioid Sarcoma 410
Clinical Features 410
Pathologic Features 411
Differential Diagnosis 411
Clear Cell Sarcoma 414
Clinical Features 414
Pathologic Features 418
Differential Diagnosis 421
Cutaneous Perivascular Epithelioid Cell Tumor (PEComa) 421
Clinical Features 421
Pathologic Features 422
Differential Diagnosis 423
Ossifying Fibromyxoid Tumor 425
Clinical Features 425
Pathologic Features 425
Differential Diagnosis 428
Pleomorphic Hyalinizing Angiectatic Tumor and Hemosiderotic Fibrolipomatous Tumor 431
Clinical Features 431
Pathologic Features 432
Differential Diagnosis 437
Solitary Fibrous Tumor 438
Clinical Features 438
Pathologic Features 438
Differential Diagnosis 442
Synovial Sarcoma 444
Clinical Features 444
Pathologic Features 445
Differential Diagnosis 449
Alveolar Soft Part Sarcoma 450
Clinical Features 450
Pathologic Features 450
Differential Diagnosis 453
Rosai-Dorfman Disease 453
Clinical Features 453
Pathologic Features 454
Differential Diagnosis 454
Cutaneous Myoepithelial Tumors 456
Clinical Features 457
Pathologic Features 457
Differential Diagnosis 463
Selected References 470
13: Miscellaneous Mesenchymal Tumors: Smooth Muscle, Skeletal Muscle, Cartilaginous, and Osseous Tumors 474
Leiomyoma 474
Clinical Features 474
Pathologic Features 475
Differential Diagnosis 476
Congenital Smooth Muscle Hamartoma 477
Clinical Features 477
Pathologic Features 477
Differential Diagnosis 478
Epstein-Barr Virus-Associated Smooth Muscle Tumors 478
Clinical Features 478
Pathologic Features 478
Differential Diagnosis 479
Leiomyosarcoma 479
Clinical Features 479
Pathologic Features 479
Differential Diagnosis 479
Rhabdomyoma 481
Clinical Features 481
Pathologic Features 482
Differential Diagnosis 482
Rhabdomyomatous Mesenchymal Hamartoma 482
Clinical Features 482
Pathologic Features 482
Differential Diagnosis 484
Cutaneous Rhabdomyosarcoma 484
Clinical Features 484
Pathologic Features 484
Differential Diagnosis 488
Soft Tissue Chondroma 488
Clinical Features 488
Pathologic Features 488
Differential Diagnosis 488
Extraskeletal Myxoid Chondrosarcoma 489
Clinical Features 489
Pathologic Features 490
Differential Diagnosis 491
Osteoma Cutis 491
Clinical Features 491
Pathologic Features 491
Differential Diagnosis 491
Extraskeletal Osteosarcoma 491
Clinical Features 491
Pathologic Features 492
Differential Diagnosis 492
Selected References 493
Correction to: Nerve Sheath and Related Tumors 496
Index 497