Pattern Analysis for Histopathologic Diagnosis of Melanocytic Lesions: A Guide to Practical Dermatopathology

Description

Pattern analysis is a powerful method that changed dermatopathology, nowadays an indispensable tool in the diagnostic workup of inflammatory and neoplastic lesions. The diagnosis of melanocytic lesions can also be mastered by pattern analysis, which is the link between pathology, dermatoscopy, and clinical dermatology and supports the integration of all views. The  histopathologic diagnosis of melanocytic lesions can be challenging for novices and experts alike. While classifications of melanocytic lesions come and go, pattern analysis is timeless; it can be assigned to any classification, current or future, and provides a framework that allows to address complex and uncertain cases in a repeatable manner. While uncertainty cannot be totally eliminated, pattern analysis helps to express this uncertainty in a meaningful way. Written by expert dermatopathologists with experience in dermatoscopy, this book is dedicated to young colleagues and to those who have not yet settled on one of the competing schools of thought; it is intended as a practical guide to help making correct observations, to describe them with a well-defined terminology, and to yield critical decisions in the face of incomplete or conflicting information. The illustrations contained in the volume are all original pictures in high-quality and full-color: reproductions of histopatological cuts in low and high magnification will assist pathologists, dermatologists, and dermatopathologists in interpreting histological slides of melanocytic skin lesions. Foreword Acknowledgments Contents About the Authors 1: Introduction 2: Historical Perspective 2.1 Melanoma 2.2 Melanocytic Nevi 2.3 The Relationship Between Melanocytic Nevi and Melanoma 3: Classifications 3.1 The WHO Classification of Melanocytic Tumors 3.2 Other Classifications 3.2.1 The MPATH-Dx Reporting Scheme 3.2.2 AJCC and TNM Melanoma Staging 3.2.3 ICD-11 and ICD-O Codes 3.3 The Relationship Between Pattern Analysis and Classifications 4: Pattern Analysis 4.1 Architecture and Silhouette 4.2 Main Patterns and Their Variations 4.2.1 Epidermal Patterns (Figs. 4.2, 4.3, 4.4, and 4.5) 4.2.1.1 Pigmented Keratinocytes, No Increase in Melanocytes (Fig. 4.2a, b) 4.2.1.2 Increased Single Melanocytes: Regular/Irregular (Fig. 4.2c, d) 4.2.1.3 Nests of Melanocytes: Arrangement, Size, Shape, and Number (Fig. 4.3a–h) 4.2.1.4 Suprabasal Melanocytes (Fig. 4.4a–d) 4.2.1.5 Epithelial Adnexal Involvement (Fig. 4.5a–d) 4.2.2 Dermal Patterns (Figs. 4.6, 4.7, and 4.8) 4.2.2.1 Single Melanocytes (Fig. 4.6a, b) 4.2.2.2 Nests (Fig. 4.6c–e) 4.2.2.3 Nodules and Sheets (Fig. 4.6e) 4.2.2.4 Interstitial Strands/Fascicles (Fig. 4.7a, b) 4.2.2.5 Periadnexal Strands/Nests (Fig. 4.7c–g) 4.2.2.6 Plexiform Fascicles (Fig. 4.7h) 4.2.2.7 Maturation (Fig. 4.8a–d) 4.2.3 Subcutaneous Pattern (Fig. 4.9a–d) 4.2.3.1 Periadnexal Strands/Fascicles 4.2.3.2 Septal Involvement 4.2.3.3 Lobular Involvement 4.2.4 Combination of Patterns 4.3 Cytology of Melanocytes 4.3.1 Shape (Fig. 4.10a–g) 4.3.1.1 Small Round 4.3.1.2 Epithelioid 4.3.1.3 Pagetoid 4.3.1.4 Spindled 4.3.1.5 Bipolar 4.3.1.6 Variants (Fig. 4.11a–f) Ancient Change Multinucleation Balloon Cell Neurotization Others 4.3.2 Pleomorphism of Melanocytes (Fig. 4.12a–f) 4.3.3 Crowding (Fig. 4.13a) 4.3.4 Mitotic Figures (Fig. 4.13b, c) 4.3.5 Necrosis (Fig. 4.13d–f) 4.4 Other Changes 4.4.1 Epidermis (Fig. 4.14a–f) 4.4.1.1 Elongated Rete Ridges 4.4.1.2 Epidermal Hyperplasia 4.4.1.3 Intracorneal Pigmentation 4.4.1.4 Kamino Bodies 4.4.1.5 Atrophy 4.4.1.6 Ulceration 4.4.2 Collagen (Fig. 4.15a–f) 4.4.2.1 Fibroplasia 4.4.2.2 Sclerosis 4.4.2.3 Desmoplasia 4.4.2.4 Scar 4.4.2.5 Collagen Changes in Regression 4.4.2.6 Solar Elastosis 4.4.3 Vessels (Fig. 4.16a–d) 4.4.3.1 Vascularization 4.4.3.2 Vascular Invasion 4.4.4 Inflammatory Infiltrates (Fig. 4.17a–f) 4.4.4.1 Halo Phenomenon 4.4.4.2 Meyerson Phenomenon 4.4.4.3 Patchy Lymphocytes/Plasma Cells 4.4.4.4 Melanophages 4.4.4.5 Lymphocytic Infiltrates in Regression 5: Integration of Patterns 5.1 Combination of Patterns and Differential Diagnosis 5.2 The Full Histologic Examination Procedure on the Basis of Examples 5.2.1 Example 1 Overall Pattern: Epidermal and Dermal, Nested, Small, Symmetric Detailed Description Silhouette Patterns Cytology Other Changes Integration 5.2.2 Example 2 Overall Pattern: Dermal, Periadnexal, and Interstitial Detailed Description Silhouette Patterns Cytology Other Changes Integration 5.2.3 Example 3 Overall Pattern: Dermal, Interstitial Detailed Description Silhouette Patterns Cytology Other Changes Integration 5.2.4 Example 4 Overall Pattern: Epidermal, Poorly Circumscribed, Single Melanocytes Predominate Detailed Description Silhouette Patterns Cytology Other Changes Integration 5.2.5 Example 5 Overall Pattern: Asymmetric, Broad, Epidermal and Dermal Detailed Description Silhouette Patterns Cytology Other Changes Integration 5.2.6 Example 6 Overall Pattern: Subcutaneous, Nodular Detailed Description Silhouette Patterns Cytology Other Changes Integration 5.3 Limitations of Pattern Analysis 6: Integration of Context 6.1 Clinical Context 6.2 In Vivo Imaging 6.3 Ex Vivo Dermatoscopy 6.4 Immunohistochemistry 6.4.1 Use Cases 6.4.1.1 Diagnosing Melanoma Without Immunohistochemistry 6.4.1.2 Rule out a Melanocytic Process 6.4.1.3 Discovery of Histologically Invisible Melanoma 6.4.1.4 Desmoplastic and Spindle Cell Melanoma 6.4.1.5 Measuring Melanoma Thickness 6.4.1.6 Atypical Spitzoid Lesions 6.4.1.7 BAP1 Deficient Nevi 6.4.1.8 Malignancy Prediction Through Immunohistochemistry 6.5 Molecular Findings 6.5.1 General Concepts 6.5.1.1 Expected-Mutation Mismatch 6.5.1.2 Interobserver Agreement 6.5.1.3 Prognosis and Therapy 6.5.1.4 Bias 6.5.2 Selected Situations 6.5.2.1 TERT 6.5.2.2 Spitzoid/Epithelioid Lesions 6.5.2.3 Blue-Like Lesions 6.6 Adding It Up: But How? 7: Pattern Analysis in Practice 7.1 Patterns 7.1.1 Junctional 7.1.1.1 Example 1: Nests and Single Cells (Fig. 7.1) Overall Pattern: Nested and Single Cells, Epidermal, Asymmetric Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.2 Example 2: Nests Mainly (Fig. 7.2) Overall Pattern: Nested, Epidermal and Dermal, Symmetric Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.3 Example 3: Nests and Single Cells (Fig. 7.3) Overall Pattern: Epidermal, Asymmetric, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.4 Example 4: Nests and Single Cells, Chronic Sun Damage (Fig. 7.4) Overall Pattern: Epidermal, Asymmetric, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.5 Example 5: Small Lesion with Nests (Fig. 7.5) Overall Pattern: Epidermal, Small, Nested, Symmetric Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.6 Example 6: Small Lesion with Nests, Heavily Pigmented (Fig. 7.6) Overall Pattern: Epidermal, Small, Symmetric, Nested, Well Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.7 Example 7: Small Lesion with Large Nests and Single Cells (Fig. 7.7) Overall Pattern: Epidermal, Asymmetric, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.8 Example 8: Small Lesion with Small Nests and Single Cells on Sun-Damaged Skin (Fig. 7.8) Overall Pattern: Epidermal, Asymmetric, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.9 Example 9: Small Lesion with Nests, Heavily Pigmented, Spitzoid (Fig. 7.9) Overall Pattern: Epidermal, Asymmetric, Large Nests Detailed Description Silhouette Patterns Cytology Other Changes 7.1.1.10 Example 10: Nests and Single Cells (Fig. 7.10) Overall Pattern: Epidermal, Asymmetric, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.11 Example 11: Single Cells and Small Nests, Facial (Fig. 7.11) Overall Pattern: Epidermal, Asymmetric, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.1.12 Example 12: Nests and Single Melanocytes, Broad Lesion (Fig. 7.12) Overall Pattern: Epidermal and Dermal, Broad, Poorly Circumscribed Detailed description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.1.2 Spindled and/or Epithelioid Pigmented, Dermal 7.1.2.1 Example 1: Pigmented Epithelioid, Dermal (Fig. 7.13) Overall Pattern: Dermal, Well Circumscribed, Interstitial Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.2.2 Example 2: Pigmented Epithelioid, Dermal (Fig. 7.14) Overall Pattern: Dermal, Plexiform, No Maturation Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.2.3 Example 3: Asymmetric Pigmented Epithelioid, Dermal and Subcutaneous (Fig. 7.15) Overall Pattern: Asymmetric, Nested and Plexiform, Dermal and Subcutaneous, No Maturation Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.2.4 Example 4: Asymmetric Pigmented Epithelioid, Dermal and Subcutaneous (Fig. 7.16) Overall Pattern: Asymmetric, Epidermal and Dermal, Well Circumscribed, No Maturation Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.2.5 Example 5: Nodular Reaching Subcutis, Heavily Pigmented (Fig. 7.17) Overall Pattern: Nodular, Well Circumscribed, Dermal and Subcutaneous, Heavily Pigmented Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.2.6 Example 6: Heavily Pigmented Dermal Nodule with Junctional Component (Fig. 7.18) Overall Pattern: Epidermal and Dermal, Asymmetric, Relatively Well Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.2.7 Example 7: Small Superficial Dermal Nodule, Pigmented Epithelioid (Fig. 7.19) Overall Pattern: Dermal, Nested, Well Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.1.2.8 Example 8: Interstitial Dark Dermal Pigmentation (Fig. 7.20) Overall Pattern: Interstitial Pigmentation, Dermal Detailed Description Silhouette Patterns Cytology Immunohistochemistry Integration 7.1.3 Epithelioid and/or Spindled Amphophilic 7.1.3.1 Example 1: Large Epidermal Nests and Epidermal Hyperplasia (Fig. 7.21) Overall Pattern: Symmetric, Epidermal and Dermal, Nested Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.3.2 Example 2: Spindled and Epithelioid Cells in a Nodule in a Child (Fig. 7.22) Overall Pattern: Epidermal and Dermal, Symmetric, Well Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.3.3 Example 3: Junctional, Epithelioid, with Kamino Bodies (Fig. 7.23) Overall Pattern: Epidermal, Symmetric, Well Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.3.4 Example 4: Dermal Nevus with Epithelioid Melanocytes (Fig. 7.24) Overall Pattern: Symmetric, Dermal, Single Cells Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.3.5 Example 5: Dermal Nodule of Pleomorphic Epithelioid Cells with Epidermal Hyperplasia (Fig. 7.25) Overall Pattern: Largely Dermal, Well Circumscribed, Nested and Interstitial Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Molecular Diagnostics Integration 7.1.3.6 Example 6: Ill-Defined Dermal Nodule of Epithelioid Pleomorphic Cells with Heavy Inflammatory Infiltrate (Fig. 7.26) Overall Pattern: Dermal Only, Interstitial, Asymmetric, and Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.1.3.7 Example 7: Asymmetric, Partly Plexiform Dermal Nodule (Fig. 7.27) Overall Pattern: Asymmetric, Dermal, Nested, and Plexiform Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.1.4 Nevoid Melanoma and Melanoma Associated with Nevi 7.1.4.1 Example 1: Dense Dermal Sheets of Melanocytes (Fig. 7.28) Overall Pattern: Symmetric, Epidermal and Dermal Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.4.2 Example 2: Dermal Sheets and Nests, Asymmetric (Fig. 7.29) Overall Pattern: Mainly Dermal, Asymmetric Nests and Sheets Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.4.3 Example 3: Very Large Nests, Epidermal (Fig. 7.30) Overall Pattern: Nested, Epidermal Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.4.4 Example 4: Biphasic Lesion (Fig. 7.31) Overall Pattern: Epidermal and Dermal, Asymmetric, Poorly Circumscribed on One Site Well Circumscribed on the Other Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.4.5 Example 5: Nodule in a Nevus Spilus (Fig. 7.32) Overall Pattern: Interstitial Sheets Throughout the Dermis Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.1.5 Regression, Sclerosis, Recurrence, and Inflammation 7.1.5.1 Example 1: Irregular Epidermal Melanocytes with Underlying Scar (Fig. 7.33) Overall Pattern: Broad, Single Melanocytes Predominate, Mostly Epidermal Detailed Description Silhouette Patterns Cytology Other Changes Elastica Stain Immunohistochemistry Integration 7.1.5.2 Example 2: Irregular Epidermal and Dermal Melanocytes with Underlying Scar (Fig. 7.34) Overall Pattern: Asymmetric, Poorly Circumscribed, Epidermal and Dermal, Some Maturation Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.1.5.3 Example 3: Traumatized Nevus (Fig. 7.35) Overall Pattern: Small, Asymmetric, Epidermal Only, Single Cells, and Nests Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.1.5.4 Example 4: Increased Epidermal Melanocytes in Melanoma Re-excision (Fig. 7.36) Overall Pattern: Asymmetric, Not Well Defined, Single Cells with Irregular Nesting Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.1.5.5 Example 5: Epidermal Nests of Melanocytes with a Lichenoid Infiltrate (Fig. 7.37) Overall Pattern: Symmetric, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2 Anatomic Sites 7.2.1 Acral 7.2.1.1 Example 1: Large Pigmented Nests (Fig. 7.39) Overall Pattern: Epidermal, Regular, Mainly Large Nests Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.1.2 Example 2: Small Nests in Epidermis and Papillary Dermis (Fig. 7.40) Overall Pattern: Epidermal and Superficially Dermal, Symmetric, Nested Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.1.3 Example 3: Asymmetric with Large Confluent Nests (Fig. 7.41) Overall Pattern: Asymmetric, Epidermal and Dermal, Nested Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.2 Face 7.2.2.1 Example 1: Single Cells in Flat Epidermis (Fig. 7.44) Overall Pattern: Epidermal, Single Cells, Asymmetric Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.2.2 Example 2: Asymmetric Horizontal Confluence and Sun Damage (Fig. 7.45) Overall Pattern: Epidermis Confluent Nests, Asymmetric Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.2.3 Example 3: Parakeratosis, Clinical Suspicion of Melanoma (Fig. 7.46) Overall Pattern: Atypical Keratinocytes, Intraepidermal Detailed Description Silhouette Patterns Other Changes Integration 7.2.2.4 Example 4: Sun Damage, Morphologically Few Visible Melanocytes (Fig. 7.47) Overall Pattern: Epidermal Only, Single Melanocytes, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.2.2.5 Example 5: Nests and Inflammation (Fig. 7.48) Overall Pattern: Single Melanocytes and Small Nests, Irregularly Distributed Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.2.3 Nail 7.2.3.1 Example 1: Asymmetric Longitudinal Nail Pigmentation (Fig. 7.49) Overall Pattern: Broad, Not Well Circumscribed, Intraepithelial Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.2.3.2 Example 2: “Onychomycosis” with Periungual Pigmentation (Fig. 7.50) Overall Pattern: Asymmetric, Nested, Epidermal and Dermal Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.3.3 Example 3: Slightly Changing Melanonychia Striata (Fig. 7.51) Overall Pattern: Small, Increased Single Cells, Some Suprabasal Detailed Description Silhouette Patterns Cytology Immunohistochemistry Other Changes Integration 7.2.3.4 Example 4: Melanonychia Striata in a Prepubescent Child (Fig. 7.52) Overall Pattern: Small, Junctional, Nested Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.3.5 Example 5: Slightly Changing Melanonychia Striata (Fig. 7.53) Overall Pattern: Subtle Pigmentation the Nail Matrix, Biopsy Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.4 “Special” Sites (Navel, Mamilla, Genital, Axilla) 7.2.4.1 Example 1: Flat Lesion on the Mamilla (Fig. 7.54) Overall Pattern: Single Melanocytes, Poorly Circumscribed, Symmetric Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.4.2 Example 2: Lesion on the Mamilla (Fig. 7.55) Overall Pattern: Nested, Epidermal and Dermal, Symmetric Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.2.4.3 Example 3: Umbilicus (Fig. 7.56) Overall Pattern: Somewhat Asymmetric, Poorly Circumscribed, Epidermal and Dermal Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.4.4 Example 4: Vulvar Pigmentation with Sclerosis (Fig. 7.57) Overall Pattern: Epidermal, Irregular, Single Melanocytes Predominate, Reaching the Margins Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.5 Conjunctiva 7.2.5.1 Example 1: Conjunctiva (Fig. 7.58) Overall Pattern: Epithelial and Lamina Propria, Nested, Pericystic Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.2.5.2 Example 2: Conjunctiva (Fig. 7.59) Overall Pattern: Nested, Epithelium and Lamina Propria Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.2.5.3 Example 3: Conjunctiva (Fig. 7.60) Overall Pattern: Well Circumscribed, in Epithelium and Lamina Propria Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.2.5.4 Example 4: Conjunctiva (Fig. 7.61) Overall Pattern: Broad Lesion, Confluence of Nests, Only Epithelial Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.5.5 Example 5: Caruncula (Fig. 7.62) Overall Pattern: Only Epithelial, Single Melanocytes Predominate Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.2.5.6 Example 6: Conjunctiva, Nonpigmented Lesion (Fig. 7.63) Overall Pattern: Epithelium and Lamina Propria, Single Melanocytes, Irregularly Distributed Detailed Description Silhouette Patterns Cytology Integration 7.3 Clinical Setting 7.3.1 Partial Biopsies 7.3.1.1 Example 1: Curetting (Fig. 7.64) Overall Pattern: Fragmented Shave Specimen, Single Melanocytes, Poorly Circumscribed Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.3.1.2 Example 2: Shave Biopsy (Fig. 7.65) Overall Pattern: Nested, Epidermal and Dermal, Well Circumscribed, Incomplete Excision Detailed Description Silhouette Patterns Cytology Immunohistochemistry Other Changes Integration Excision: Nodular Lesion After Shave Biopsy (Fig. 7.66) Overall Pattern: Nodular, Ulcerated, Epidermal and Dermal Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.3.1.3 Example 3: Punch Biopsies of a Large Lesion on the Face Punch Biopsy 1 (Fig. 7.67) Punch Biopsy 2 (Fig. 7.68) Overall Pattern: Epidermal and Dermal, Irregular Single Melanocytes, Two Biopsies from One Lesion Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration Excision (Fig. 7.69) Overall Pattern: Epidermal and Dermal, Irregular Single Melanocytes Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.3.1.4 Example 4: Small Nests and Single Melanocytes, Biopsy of a Large Lesion (Fig. 7.70) Overall Pattern: Epidermal Only, Single Cells Predominate, Biopsy Detailed Description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.3.2 Newborns, Babies, and Children 7.3.2.1 Example 1: Lesion of a 3-Week-Old Infant (Fig. 7.71) Overall Pattern: Large Nests and Interstitial Strands in the Entire Dermis Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.3.2.2 Example 2: Lesion of a 9-Week-Old Infant (Fig. 7.72) Overall Pattern: Asymmetric, Epidermal and Dermal, Nested and Interstitial Detailed Description Silhouette Patterns Cytology Other Changes Integration 7.3.2.3 Example 3: Dermal Lesion with Thin Epidermis in a Child (Fig. 7.73) Overall Pattern: Polypoid, Largely Dermal, Adnexocentric Detailed description Silhouette Patterns Cytology Other Changes Immunohistochemistry Integration 7.3.2.4 Example 4: Nodule Arising in a Congenital Nevus in a Newborn (Fig. 7.74) Overall Pattern: Dermal and Subcutis, Nodules and Sheets Detailed Description Silhouette Patterns Cytology Other Changes Integration 8: Bias, Noise, and Error 8.1 Last Words References Index