Fundamentals of dermoscopy

Transcription

1 Fundamentals of dermoscopy Learning objectives Upon completion of this session, participants should be able to: describe the basic principles of dermoscopy identify features associated with pigmented and non pigmented lesions identify features associated with benign and malignant lesions recognise the role of dermoscopy in diagnosing skin lesions list the alternative uses for dermoscopy in general practice put into place a systematic checklist to aid in preoperative diagnosis of skin lesions in clinical practice 2 Overview The device Dermoscopic criteria (terminology) Colour Patterns Global features Local features Approach to diagnosing pigmented lesions Approach to non melanocytic lesions Other uses in general practice 3

2 The device Also called: Dermatoscopy Epiluminoscopy Epiluminescent microscopy 4 Dermoscopic criteria Terminology used in dermoscopy 5 Colour Black Epidermis Light to dark brown Dermal-epidermal junction Ink-spot naevus Blue-grey Papillary dermis Benign mole Steel blue Reticular dermis Superficial spreading melanoma Subcutaneous tissue Blue naevus 6 2

3 Colour White Red Red-black/blue-black Regressive, scar-like regions Cherry angioma Blood clot White Yellow Purple Keratin Keratin Haemangioma 7 Pattern: Global features Reticular pattern lesion predominantly made up of a mesh-like pigment network Seen in: benign acquired melanocytic naevi thin melanomas. Globular pattern lesion mostly covered with numerous round-to-oval structures Frequently seen in: acquired melanocytic naevi congenital naevi seborrhoeic keratoses Dysplastic naevi 8 Pattern: Global features Pseudo-network Rough pigment network found on the face Clear spaces surround the openings of the hair follicles and sweat glands Seen in benign naevi, lentigines, solar keratoses, lichenoid keratoses and early lentigo maligna These may be difficult to differentiate from each other. 9 3

4 Pattern: Global features Homogeneous pattern Starburst pattern Cobblestone pattern Parallel pattern Lacunar pattern Unspecific pattern 0 Pattern: Global features Uniform colour; absence of pigment network or local structures. If mainly bluish colour, this is a hallmark of blue naevus. Also seen in: Clark s naevi dermal naevi nodular and metastatic melanomas thrombosed haemangiomas subungual haematomas subcorneal haemorrhages pigmented basal cell carcinomas tattoos Homogeneous pattern Starburst pattern Cobblestone pattern Parallel pattern Lacunar pattern Unspecific pattern 0 LSK-2-06 Pattern: Global features Radial streaks at the periphery of the pigmented lesion. Homogeneous pattern Usually seen in: Reed naevi (benign moles usually found in children) malignant melanomas Starburst pattern Cobblestone pattern Parallel pattern Lacunar pattern Unspecific pattern 0 4

5 Pattern: Global features Homogeneous pattern Starburst pattern A group of angulated oval-to-round structures resembling cobblestones. Larger than globules. Papillomatous dermal naevi (a raspberry-like mole) Congenital naevi Compound Dysplastic naevi Seborrhoeic keratoses Cobblestone pattern Parallel pattern Lacunar pattern Unspecific pattern 0 Pattern: Global features Homogeneous pattern Starburst pattern Cobblestone pattern Found exclusively on the palms and soles. Acral melanocytic naevi Acral melanomas Parallel pattern Lacunar pattern Unspecific pattern 0 Pattern: Global features Homogeneous pattern Starburst pattern Multiple smooth round-tooval structures in a striking red, blue-purple or black colour. Cobblestone pattern Hallmark of haemangiomas and angiokeratomas Parallel pattern Lacunar pattern Unspecific pattern 0 5

6 Pattern: Global features Homogeneous pattern Starburst pattern Cobblestone pattern This term is used when none of the global features mentioned can be identified within the lesion. No real diagnostic implication but often associated with melanoma Parallel pattern Lacunar pattern Unspecific pattern 0 Dermal papillae * Typical pigment network Rete ridges Atypical pigment network Pigment network A grid of thin brown lines over a diffuse light brown background Can be likened to a honeycomb where the reticulation or network represents the rete ridge pattern of the epidermis The hypopigmented holes correspond to the tip of the dermal papillae Defines a pigmented lesion as melanocytic, with two exceptions dermatofibroma and extra nipple. Typical and atypical pigment networks A pigment network can be typical or atypical: A typical network is relatively uniform, evenly spaced, evenly coloured and usually thinning out at the sides An atypical network shows irregular thickness and darkened lines, which may end abruptly at the periphery (Refer to arrow pointing to broadened network) Areas devoid of any type of network without abnormal local features, such as scarring or globules, are called structureless areas Typical network Found in Dysplastic naevi, lentigo simplex, solar lentigo, dermatofibroma Atypical network Melanoma 6

7 Dots Globules Streaks Radial streaming Pseudopods Moth-eaten borders 2 Dots Small round dots, <0. mm. Dots Globules Symmetrical Round to oval Size >0. mm Represent nests of melanocytes, melanin clumps or melanophages in the lower epidermis, dermoepidermal junction or upper papillary dermis Colour depends on depth of pigment Globules Dots and globules are found in both benign and malignant melanocytic lesions. Benign proliferations Regular in size and shape Evenly distributed (mostly central) Malignant melanoma Vary in size and shape Predominantly found in the periphery 2 Streaks Linear extensions, most clearly seen at the periphery of the lesion Streaks Can be regular or irregular Include radial streaming, radial streaks and pseudopods Regular, symmetrical streaks spindle-cell (Reed) naevus Irregular streaks melanoma Radial streaming 2 7

8 Pseudopods Finger-like projections with knob-like endings. Specific feature of superficial spreading melanoma. Pseudopods Moth-eaten borders Concave edges, like a moth-eaten cloth. Moth-eaten borders Seen in: freckles flat seborrhoeic keratoses benign and malignant lentigines. 2 Hypopigmentation Regression structures Blue-white veil Blue-grey ovoid nests Spoke-wheel-like structures Ulceration 3 Hypopigmentation Localised or wide area that is lighter than the surrounding lesion. Atypical naevi Melanoma Hypopigmentation Regression structures Regression structures White scar-like zones and/or blue-grey diffuse or speckled areas (peppering) White areas represent fibrosis; blue-grey areas represent melanosis (darkening from pigment-laden macrophages) Histologically different from blue-white veil but may be difficult to distinguish visually Atypical naevi (Clark s naevi) Melanomas Lichen planus-like keratoses 3 Pigmented solar keratoses 8

9 Blue-white veil Blue pigmentation with an overlying hazy, white film. Specific to malignant melanomas. Blue-white veil Blue-grey ovoid nests Blue-grey ovoid nests 3 Large, well-circumscribed, pigmented ovoid structures that are larger than globules Can form confluent groups Not connected to tumour body Highly suggestive of basal cell carcinoma (especially in the absence of a network). 3 Spoke-wheel-like structures Spoke-wheel-like structures Radial projections from a darker centre, similar to the spokes of a bicycle wheel. Basal cell carcinoma. Ulceration Absence of epidermis with dried blood; no history of trauma. Basal cell carcinoma (if no network) Invasive melanoma Ulceration 3 Comedo-like openings Milia-like cysts Fissures and ridges Central white patch Leaf-like areas Fingerprint structures 4 9

10 Comedo-like openings Also called crypts or pseudofollicular openings Blackhead plugs filled with keratin Comedo-like openings Mostly seen in seborrhoeic keratoses Papillomatous dermal naevi (i.e. Unna naevi; bumpy, raspberry-like appearance) Milia-like cysts Round, white-to-yellow keratin cysts Also known as horny pseudocysts Seborrhoeic keratoses Papillomatous dermal naevi (Unna naevi) Milia-like cysts 4 Fissures (arrow) and ridges (asterisk*) Brain-like pattern. Seborrhoeic keratoses. Fissures and ridges Central white patch 2 Sharp, crystal-white area; surrounding pigment lesion is otherwise regular. An exclusive feature of dermatofibroma. Central white patch 4 Leaf-like areas Discrete bulbous blobs with leaf-like pattern (maple leaf appearance) Colour ranging from brown to bluish-grey Leaf-like areas Pigmented basal cell carcinoma. Fingerprint structures Description Fine parallel ridges similar to fingerprints. Solar lentigo. Fingerprint structures 4 0

11 Red lacuna Wreath-like vessels Arborising vessels Comma vessels Dotted vessels Hairpin vessels 5 Red lacuna Well-defined oval or round lakes representing dilated vascular spaces Can be red, bluish-red, dark red or black (darker colour if thrombosed) Red lacuna Exclusively seen in haemangiomas and angiokeratomas Other variations: haematomas under the toenail or cornea 5 Red lacuna Angiokeratoma Wreath-like vessels Sebaceous hyperplasia Arborising vessels BCC Comma vessels Compound or Dermal naevi Dotted vessels Spitz naevi or melanoma Hairpin vessels Melanoma and Seb Keratosis 5

12 Approach to diagnosing pigmented lesions Two step procedure for differential diagnosis of pigmented skin lesions: Step : Differentiate between melanocytic and non melanocytic lesions Step 2: Differentiate between benign melanocytic lesions and melanoma 6 Step Melanocytic vs. non melanocytic lesions Criteria Pigment network Pseudonetwork Aggregated globules Branched streaks Parallel pattern NO Criteria Homogeneous blue area NO Criteria Milia-like cysts Comedo-like openings Fissure ridges Hairpin blood vessels Moth-eaten border Fingerprint structures Network-like structures NO YES YES YES Melanocytic lesion Blue naevus Seborrhoeic keratosis 7 Soyer HP, et al. Color Atlas of Melanocytic Lesions of the Skin. Germany: Springer-Verlag; Step Melanocytic vs. non melanocytic lesions NO Criteria Red, blue-black lacunae Red-bluish to red-black homogeneous areas NO Criteria Arborising vessels Leaf-like areas Blue-grey ovoid nests Large blue-grey globules Spoke-wheel areas Ulceration Criteria None of the above NO YES YES YES Haemangioma Angiokeratoma Basal cell carcinoma Melanocytic lesion Soyer HP, et al. Color Atlas of Melanocytic Lesions of the Skin. Germany: Springer-Verlag;

13 Step 2 Benign vs. malignant melanocytic lesions 3 point checklist,2 Asymmetry Atypical network Blue white structures If lesion fulfils 2 criteria = suspicious lesion; biopsy 7 point checklist 3 Major criteria Points Atypical pigment network 2 Blue-white veil 2 Atypical vascular pattern 2 Minor criteria Irregular streaks Irregular pigmentation Irregular dots/globules Regression structures Score < 3 = Benign Score 3 = Malignant melanoma. Campos-do-Carmo G, Ramos-e-Silva M. Int J Dermatol. 2008;47: DermNet NZ. Three-point checklist Argenziano G, et al. Arch Dermatol. 998;34: point checklist Using the 3 point checklist, determine if the following lesions require biopsy 20 Case Asymmetry Atypical network Blue white structures 2 3

14 Case 2 Asymmetry Atypical network Blue white structures 22 Case 3 Asymmetry Atypical broad pigment network Blue white structures 23 7 point checklist Using the 7 point checklist, determine if the following lesions require biopsy 24 4

15 Case 7-point checklist Major criteria Points Atypical pigment network 2 Blue-white veil 2 Atypical vascular pattern 2 Minor criteria Irregular streaks Irregular pigmentation Irregular dots/globules Regression structures 25 Case 2 7-point checklist Major criteria Points Atypical pigment network 2 Blue-white veil 2 Atypical vascular pattern 2 Minor criteria Irregular streaks Irregular pigmentation Irregular dots/globules Regression structures 26 Case 3 7-point checklist Major criteria Points Atypical pigment network 2 Blue-white veil 2 Atypical vascular pattern 2 Minor criteria Irregular streaks Irregular pigmentation Irregular dots/globules Regression structures 27 5

16 Dermoscopy for non melanocytic pigmented lesions Case studies 28 Case study Presentation 48 year old man Red macular rash on left cheek 5 x 8 mm lesion with rough, keratotic surface Dermoscopy Red pseudonetwork Unfocused large-calibre vessels between the hair follicles (strawberry pattern) Prominent follicular openings surrounded by white halo 29 Dermoscopic features of solar keratoses Non pigmented Pigmented Strawberry pattern Vessels are linear wavy, or small coiled or dotted Peris K, et al. J Dtsch Dermatol Ges. 2007;5: Dots and globules around hair follicles Annular granular pattern Pseudonetwork 30 6

17 Differential diagnoses Bowen s disease Seborrhoeic keratosis Basal cell carcinoma Clear cell acanthoma 3 Case 2 History 68 year old man With scaly rash on scalp Itchiness and thinning hair Family history of psoriatic arthritis Personal history of basal cell carcinoma 5 years ago Physical examination 5 x 8 cm flaky, silvery white lesion on erythematous plaque on scalp Dry, non tender, indurated Whole body skin check no findings Nails and joints unaffected 32 Additional information This is a dermoscopic view of the lesion 33 7

18 Differentiating scalp psoriasis from other lesions with dermoscopy Psoriasis Tinea capitis C Seborrhoeic dermatitis B Image A used with permission from Kim GW, et al. Br J Dermatol. 20;64: Image C used with permission from Crocker Sandoval AB, et al. Rev Iberoam Micol. 200;27: Other uses of dermoscopy in general practice Burrows Common wart Cutaneous lupus Lichen planus Porokeratosis Sebaceous hyperplasia 35 Conclusion Dermoscopy is useful for assessing benign/malignant melanocytic and non melanocytic lesions, and other conditions in general practice More accurate diagnosis of skin cancers reduces specialist referrals and surgical procedures Pitfall: false negatives resulting in underdiagnosis of melanoma Users should receive appropriate training and continue to improve their skills Dermoscopy should be viewed as a diagnostic aid and not replace good clinical skills 36 8