4 Medicine

C o n t e n t s
4.1 Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

by Bryan C. Markinson, DPM

4.2 Diabetes Mellitus and Wound Care . . . . . . . . . . . . 255 by Nabil Fahim, DPM and Mark Mandato, DPM 4.3 Emergency Medicine in the Podiatric Office . . . . . 277 by Melvyn Grovit, DPM, MS, CMS 4.4 Podiatric Infectious Disease . . . . . . . . . . . . . . . . . 283 by Mark Kosinski, DPM 4.5 Internal Medicine . . . . . . . . . . . . . . . . . . . . . . . . 303 by Sushama Rich, MD 4.6 Neurology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343 by Lawrence Diamond, MD 4.7 Peripheral Vascular Disease . . . . . . . . . . . . . . . . . 357 by Arthur Steinhart, DPM 4.8 Pharmacology . . . . . . . . . . . . . . . . . . . . . . . . . . . 365 by Gus Constantouris, DPM 4.9 Rheumatology . . . . . . . . . . . . . . . . . . . . . . . . . . . 405 by Arthur Steinhart, DPM

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4.1

Dermatology

Bryan C. Markinson, DPM

Introduction To The Review for Dermatology

During my fellowship training, my mentor, W. Clark Lambert, MD Ph.D., reminded me more than once that there were some 3500 skin diseases. He would say, If every podiatrist would examine every patients skin up to the tibial tuberosity, he or she would pretty much be certain to encounter the vast majority of them. Taking him at his word, I am pretty certain that I have not yet encountered 3500 different diseases, but increasing just the anatomic boundaries of my examination as he suggested has changed my practice greatly. The depth of this chapter will not approach the magnitude of clinical volume that Dr. Lambert states exists on the lower extremities. It is not designed for that task. However, it has been compiled with his admonition in mind. This dermatology review is specifically designed to be a source of compact information on skin diseases. Since many podiatric board questions are given in case format, knowledge of organ-specific disease processes must be studied from a broad perspective. For example, while psoriasis may cause pitting nail changes, it is important to know that it may be part of a larger clinical picture in a patient presenting with distal inter-phalangeal joint arthritis. Similarly, a case presentation centered on a neurotrophic foot ulceration may require you to be able to identify causes of neuropathy other than diabetes. So preparing for this examination requires knowledge of not only specific skin lesions but their relationship to the general medical condition of the patient as well. Indeed, many of the skin conditions discussed will overlap with your studies of internal medicine, infectious disease, diabetes, etc. It is strongly urged that you use this review chapter along with a good color atlas of dermatology to view the lesions. In addition, unfamiliar terminology should be reviewed with an appropriate text. In an attempt to make the review comprehensive and at the same time quickly usable, I have listed the disease entity by name in bold and followed with specific bulleted key points about the condition. You can think of these as points to pass. I am confident that they should closely represent the information that would be required of you in most cases. The diseases are not grouped in any specific fashion. Of course, no guarantee can be made as to the absolute utility of this review chapter. In past years however, approximately 1,000 doctors of podiatric Medicine have been presented this material in lecture format and we have received an overwhelmingly favorable response. Best wishes to you for success on your examinations. Bryan C. Markinson, D.P.M.

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The Patient Examination

The Dermatological History Chief complaint Onset of symptoms Factors that exacerbate or alleviate condition Response to prior treatments Are lesions related to work environment? Are lesions induced or worsened by sun exposure, cold, heat, dryness, or hydration? Is skin disease associated with fever? Has previously stable lesion changed in any way?

Examination of the Skin

Observation Color Topography Gross abnormalities Discharge Hair distribution Palpation - nodules, elevation, hardness, hydration, etc. TSAD METHOD Type: Primary or secondary lesion Shape: dome, flat-topped, polygonal, linear, annular, serpiginous Arrangement: Annular, Linear, or serpiginous grouping Distribution: Symmetrical, dermatomal, segmental, random, localized, generalized In a podiatric medical evaluation, the skin of the entire lower leg and foot should be exposed. The room should be well-lit. With completely undressed patients, make every effort to preserve modesty.

Physical Diagnostic Tools

Magnifying lens: 2x-10x - helpful in examining pigment deposition and used to observe dilated nail fold capillaries in connective tissue diseases Mineral oil: Applying to certain lesions will highlight pattern of colors. Useful in enhancing pigment, nail fold capillaries, and striae Side lighting: Causes textural changes of the skin to cast shadows, thus making them more visible. Can be done with a penlight beam aimed transversely over the lesion. This technique demonstrates elevations and depressions, which are characteristic of certain lesions. Example: Elevation of purpura in vaculitis Diascopy: The application of or pressing of flat transparent glass on the skin to blanch away redness. Allows true color evaluation, as well as helping to differentiate between purpura and vessel inflammation Woods lamp/light: Emits long-wavelength ultraviolet light (black light). The exam is done with room lights off. Uses for Woods lamp: Assess amount and location of skin pigment De-pigmented areas fluoresce bright white. Hypo-pigmented areas become more visible but do not fluoresce brightly. Hyper-pigmented areas appear darker than adjacent skin when pigment in epidermis. Dermal pigmentation is not enhanced.

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Erythrasma (corynebacterium) fluoresces coral red. Tinea capitis (M. canis, M. audouini) fluoresces green. Rare on feet. Gram stain for pathogenic bacteria Take specimen (pus) and fix with methyl alcohol Crystal violet stain Grams iodine Alcohol decolorizer Alcoholic safranin Fungal scraping or KOH mount Direct examination of fungal hyphae Use #15 blade to scrape leading edge of lesion Apply KOH and heat without boiling to dissolve keratin Observe for hyphae Does not allow for species identification Fungal culture Saborauds agar or DTM (color indicator) Useful for dermatophtyes and candida - scrapings of skin implanted on media May take up to three weeks For nail specimens, use most proximal, subungual debris Tzanck smear Used for diagnosis of herpes virus infections Identifies multinucleated giant cells Base of a vesicle is scraped and material is put on slide, air dried, and then heat fixed Add Giemsa stain and allow to dry Examine under microscope Wound culture Biopsy Punch Shave Excision curettage

When to Biopsy
To establish a diagnosis To remove a tumor and check its margins Biopsy surgery Definitive surgery To assess the efficacy of a therapeutic procedure To avoid unnecessary or debilitating treatments

Which Lesion Do I Biopsy?

Best lesions are well-developed. Exception: Vesicular, bullous or pustular lesions are best biopsied in 24-48 hours Multiple biopsies where lesions are present in various stages may save time Areas of excoriation, rubbing, and application of medications should be avoided

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Skin Biopsy Methods

Punch Shave Scissors Curettage Incisional Elliptical (or fusiform) excisional

Other Biopsy Considerations

Do I have an idea of what the lesion is? For Example: Warts, seborrheic keratoses require different planning than lesions of scleroderma or melanocytic lesions try to anticipate the pathological defect. A working differential is important as the kind, type, and depth of appropriate surgery will change! A punch biopsy is inadequate for pathologic processes of fat such as morphea, panniculitis, erythema nodosum, and scleroderma A punch of less than 4 mm is inadequate for inflammatory conditions Processes in the deep to lower dermis require scalpel incisional biopsy

Diseases
Psoriasis
Often symmetrical Most commonly on extensor surfaces (knees, elbows, nails) Presents as erythematous patches and plaques covered with white scales Associated with the Auspitz sign tugging gently on scale results in bleeding Associated with arthritis, classically sero-negative and exhibiting a predilection for the distal inter-phalangeal joints

Guttate Psoriasis
Guttate is Latin for drop-like. These lesions are therefore similar in color and texture but they are shaped like drops or smaller circular lesions than in the classic form

Pustular Psoriasis
Characteristically presents as multiple, fresh, yellow pustules AND older, dry, brown macules on the palms and soles Must be differentiated and is classically mis-diagnosed as vesicular tinea pedis

Psoriatic Nail Disease (Classic Changes)

Oil-drop staining Pitting small depressions on the surface of the nail plate Sub-ungual debris and hyperkeratosis Transverse grooves Looks clinically very similar to onychomycosis and may indeed coexist with onychomycosis

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Lichen Simplex Chronicus

Hallmark finding clinically is history of chronic rubbing and scratching Accentuation of skin lines, known as lichenification, is very evident Frequently on extremities and neck region, anal area, back of neck Hyper-pigmentation and scaling very typical Anterior ankle area very common podiatric presentation rubbing produced by opposite heel Rarely evident in an area where the patient cannot reach with hands Excoriation may be present An exaggerated form is known as prurigo nodularis May be associated with certain personality type Treatment directed at stopping the itch-scratch cycle High-potency steroids usually required for symptomatic relief for lesions on the lower extremities

Atopic Dermatitis
Typically associated with history of allergies and/or hay fever in patient OR family members Increased flexion creases in palms and soles Dry skin Circumoral pallor Nail fold changes Lesions commonly on dorsum of feet, antecubital fossa, popliteal fossa, neck, and face

Mycosis Fungoides
This is a form of cutaneous T-cell lymphoma (CTCL) Presents with patch, plaque and tumor stages Varying shades of red to violaceous Systemic form with peripheral blood involvement is the Sezary syndrome

Scabies
Characteristic lesion is a burrow caused by the female of the mite Sarcoptes scabei Palms and soles, sides of toes, web spaces are common locations. It is a mite infestation Hallmark clinical sign is very intense pruritis

Lichen Planus
Typically present as violaceous polygonal papules May coalesce into plaques. Predilection for flexural surfaces, especially wrists and ankles Pruritis may be prominent. Classic destruction of nail matrix with ablation/deformity of nail plate is called pterygium

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Granuloma Annulare
Annular (circular) lesions with elevated periphery Central areas of lesions exhibit clearing Common on dorsum of foot Usually self-limiting and requires no treatment unless there is severe itch. This lesion is one of the palisading granulomas based on histologic changes. Other palisading granulomas are necrobiosis lipoidica, rheumatoid nodule, and nodules of rheumatic fever

Hand-Foot-and-Mouth Disease
Causative agent is Coxsackie A16 virus Ulcerative lesions found in the mouth Erythematous macules and papules with central gray round to oval vesicles on fingers, hands, toes, and feet Resolves in 7-10 days

Secondary Syphilis
Called the great imitator as it resembles many other lesions Clinical presentation is varied Scaly erythematous plaques of palms and soles Macular-papular rash often described as salmon or ham colored Should be in differential of many plantar dermatoses Spirochete is causative organism

Warts (Verrucae)
Caused by the DNA containing human papilloma virus (HPV) There are over 100 types of HPV, some are associated with malignancy Four types of clinical lesions are vulgaris, plantaris, plana, and condyloma acuminatum Clinically evident black dots within cauliflower-like keratosis and soft yellow centers are common clinical descriptions Black dots represent cutaneous hemorrhage from tips of dermal papillae Human papilloma virus, in addition to warts, also causes Bowenoid papulosis, verrucous carcinoma, and epidermodysplaia verruciformis

Plantar Wart
Mostly under areas of pressure but do not have to be Maybe solitary or grouped Several solitary lesions may fuse forming a mosaic Black dots prominent except in early lesions Soft central clear to yellow core Classically described as painful on lateral compression Pinpoint bleeding noted on debridement represents papillomatosis where-in papillary dermis is actually above the epidermis, causing transection of papillae and resulting bleeding

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Erysipelas
Caused by group A beta-hemolytic strep Painful, well-defined lesion commonly on lower leg Edematous Raised margins

Cellulitis
Erythematous process Warm to hot Strep and staph most common organisms Poorly defined borders By definition, involves skin and subcutaneous tissues

Ecthyma
Painful indurated plaque Group A beta strep Becomes necrotic with crusting

Impetigo
Staph aureus and beta hemolytic strep are causes Bullous and non-bullous forms exist. Hallmark is honey colored crusts Lesions clear centrally.

Furuncle
Infection of the hair follicle On feet, commonly seen on hair bearing portions of the dorsal aspect Commonly due to staph aureus Develops into a painful erythematous nodule Several furuncles may coalesce into a carbuncle (boil)

Pitted Keratolysis
Typically occurs in the presence of hyperhidrosis Very common on heels Malodor may be prominent Discrete plantar pits within macerated skin is hallmark feature Diphtheroids are causative organisms. Responds very well to systemic erythromycin Topical erythromycin may also be used Therapy directed towards hyperhidrosis is helpful

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Tinea Pedis
This disease should be known very well. It is a form of superficial fungal infection. Any aspect of it should be considered fair game. In general, tinea pedis is classified into three general types: acute inflammatory, chronic or dry scaly, and interdigital. Some texts discuss four types, dividing interdigital into dry and moist types. You should study the fungal organisms as well.

Acute Inflammatory Tinea Pedis

Deep vesicles and bullae are present Bullae are multi-locular Typical location is in the long arch May become eroded in severe cases Trichophyton mentagrophytes, a dermatophyte, is most common organism Drainage of the blisters provides some pruritis relief. Topical anti-fungals work rapidly Topical steroid may be required in severe cases to control pruritis

Chronic or Dry-Scaly Tinea Pedis

Typically erythematous, dry, and scaly Typically present in moccasin or sandal distribution Trichopyhton rubrum is most common organism Often associated with concomitant onychomycosis

Interdigital Tinea Pedis/Tinea interdigitale

Fissuring and or scaling of toe web Degree of maceration varies May become super-infected with bacteria and become a cause of chronic cellulitis Trichophyton mentagrophytes is common organism, but infection often mixed When super-infected with pseudomonas, a green tinge overlying maceration may be present May progress to gram-negative tinea pedis and ascending cellulitis requiring IV antibiotics

Onychomycosis: Recognized Types

Distal Subungual (most common) White Superficial (common) Proximal Subungual (uncommon) Candida Lateral nail fold

Distal Subungual Onychomycosis (DSO)

Primarily involves distal nail bed and hyponychium Secondarily involves underside of nail plate Results in a dermatitis that causes subungual hyperkeratosis and uplifting of nail plate caused by T. Rubrum

Most commonly

White Superficial Onychomycosis (WSO)

Primarily involves surface of nail plate. Opaque, chalky, white islands are seen. Nail plate becomes soft, rough, and crumbly. T. Mentagrophytes most common causative agent

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Proximal Subungual Onychomycosis (PSO)

Same as distal subungual type but organisms infect via proximal nail fold Most proximal portions of nail plate involved White areas move distally as nail grows Seen with greater frequency in HIV infection, may be considered by some as a marker for the disease

Candida Onychomycosis
Direct invasion by candida in chronic muco-cutaneous candidiasis Opaque white strands Pseudo-clubbing of distal digits Distinct from candida paronychia

Lateral Nail Fold Onychomycosis

Essentially the same as DSO, except confined to medial or lateral nail fold

Most Common Organisms in Onychomycosis

Dermatophyte fungi - 91% - T. Rubrum, T. Mentagrophytes, E. Floccosum Yeasts - 6% - Candida, other species Non - dermatophyte molds - 3% - Aspergillus, Scopulariopsis, Scytalidium, others Summerbell RC et al. Mycoses 1989; 32:609-19.

Erythrasma
Caused by diphtheroid c. minutissimum Affects intertriginous areas Woods light examination reveals coral red fluorescence due to the porphyrin ring structure in the organism. Round to oval patches with maceration and scaling interdigitally Treatment with erythromycin orally or topically

Mycetoma A Deep Fungal Infection

Presents with draining sinuses May progress to fungal osteomyelitis Usually requires surgery and systemic anti-fungal therapy Infection often occurs outside of United States

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Larva Migrans
Also called creeping eruption Severe pruritis is common Visible erythematous tract on the skin Caused by the dog or cat hookworm, ancylostoma braziliense May be eradicated with topical ethyl chloride to the caudal end or systemic thiabendazole

Diabetic Dermopathy
Round to oval brown lesions Typically on the anterior aspect of the lower legs Usually the lesions are atrophic Clinically similar to post-inflammatory pigmentary changes

Necrobiosis Lipoidica
Yellow, indurated, atrophic, plaques on lower extremities May ulcerate Occurs 75% in women Not always associated with diabetes 67% of patients affected are diabetic, but necrobiosis lipoidica is a rare complication of diabetes - .39% One of the palisading granulomas

Bullous Diabeticorum or Diabetic Bullosa

Multiple bullae on feet and toes Typically present with angular borders, which differentiate them from friction lesions, which are typically rounded Fluid in the bullae is sterile Bullae seemingly appear without provocation

Leukocytoclastic Vasculitis (LVA)

Vessel inflammation causing bleeding into the skin resulting in a non-blanching erythema called purpura. Because the bleeding is high in the skin, it is a palpable purpura Lesions can ulcerate and form black eschars due to local ischemia It may represent a drug reaction sulfonylureas are a well-known cause May coexist with collagen vascular disease LVA itself is merely a histologic description of this entity, which may occur in association with other diseases

Henoch Schonlein Purpura

This is an immune complex deposition disease Commonly occurs in children accompanied by joint pain, hematuria, and abdominal pain Histologically, it is LVA:

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Erythema Nodosum
Histologically, this disease is a septal panniculitis, or inflammatory reaction in the subcutaneous fat involving the fibrous septae between fat cells Large areas of tender, erythematous nodules on anterior legs; can break down Represents a hypersensitivity response to strep infections, tuberculosis, deep mycoses, sarcoidosis, ulcerative colitis, drugs (commonly oral contraceptives, laxatives) May be associated also with Chrohns disease and Bechets syndrome Other infections: TB, Coccidiomycosis, Histoplasmosis, Yersinia, Leprosy May be idiopathic up to 40% of cases

Nodular Vasculitis - Erythema Induratum (Bazins Disease)

Histologically, this disease is a lobular panniculitis, or inflammatory reaction in the subcutaneous fat involving the fat cell itself Called Induratum or Bazins disease when associated with tuberculosis Tender erythematous nodules that ulcerate and scar on the posterior calf area Most clinicians will treat for tuberculosis even if patient tests negative

Livedo Reticularis
More of a reaction pattern than true disease Presents as a fish net pattern of erythema on lower extremities May accentuate on exposure to cold Must be differentiated from cholesterol embolization May herald the onset of systemic vasculitis or collagen vascular disease

Raynauds Phenomenon
Occurs on exposure to cold Manifested by severe vasospasm Characteristically presents with the tri-phasic color change of rubor-pallor-cyanosis Many patient present with different areas of the feet in different phases of the color change Symptoms are coldness, numbness, pain, burning Underlying causes should be ruled out such as collagen vascular disease, cryoprecipitants, internal malignancy When no underlying cause is found, the condition is termed Raynauds disease

Keratoderma Blennorragicum (KDB)

Associated with Reiters Syndrome: Diagnostic criteria: one month of arthritis in association with urethritis. Arthritis is in knees, ankles, and feet Adjunctive findings: conjunctivitis, circinate balanitis and keratoderma blennorragicum KDB - vesicles, papules, and macules early, becoming pustular, keratotic and crusted. Nail and mucous membrane changes as well

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Pemphigus Vulgaris
A serious, acute or chronic, bullous, autoimmune disease of skin and mucous membranes Can be fatal. Cell adhesion lost Often starts orally, progresses to skin. Lesions are painful Patients feel weakness, malaise; Weight loss due to inability to eat Bullae rupture easily, are flaccid, and weeping and lead to erosion Exhibit Nikolsky sign pressure on bulla causes dissection of fluid and expansion of bulla Hospitalization may be required Steroids: 2-3mg/kg prednisone Immunosuppressive therapy: Azathioprine, Methotrexate, Cyclophosphamide, Plasmapheresis, Gold

Bullous Pemphigoid
Autoimmune bullous eruption similar but less severe than pemphigus Commonly occurs first on lower legs, as well as axillae, thighs, abdomen, forearms Large oval or round bullae Labs: Indirect immunofluorescence reveals anti-basement membrane IgG Treatment: Systemic prednisone; May be combined with azathioprine Mild cases may respond to topical treatment

Pyoderma Gangrenosum
Usually presents as deep-seated nodule or pustule, which breaks down to form a large ulcer with serous/purulent/ hemmorhagic drainage Weeping is extensive and continuous Edges of lesion are raised, undermined, irregular and necrotic edges develop Associated with inflammatory bowel (large and small) disease, arthritis, and internal malignancy (hematopoietic myeloma, leukemia), diverticulitis, Bechets syndrome

Neurotrophic Ulceration (Mal perforans)

Typically on or under a bony prominence Vascularity typically good Diabetes, leprosy, spinal syndromes, alcoholism, nutritional diseases, pernicious anemia are among the causes of neuropathy

Rheumatoid Nodules
One of the palisading granulomas Moveable firm nodules present in RA patients May ulcerate May become infected and discharge fluid No treatment necessary unless symptomatic or infected May rarely precede the onset of clinical arthritis

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Seborrheic Keratosis
Roughened, verrucous surface Varying shades of brown, may be deeply pigmented Slightly raised, stuck-on appearance Very common on the lower legs, especially in elderly women Called dermatosis papulosa nigra on the face of African-Americans Melanoma is in the differential diagnosis, as is basal and squamous cell carcinoma

Epithelioma Cuniculatum or Squamous Carcinoma

Plantar foot is common location for this variant May be mistaken for large verruca A cheesy discharge can be expressed from crypts within the lesion representing degenerated keratin Malodorous Requires surgical excision May metastasize

Basal Cell Carcinoma

The most common of all malignancies in humans Very rarely metastasizes slow growing Most frequent in men over 50 years old Rare on feet but does occur Classically described as an ulcer surrounded by a pearly or waxy border Telangiectases are a hallmark finding

Dysplastic Nevus (Atypical Mole)

Precursor lesion of melanoma 1992 NIH consensus panel on proper terminology since 1992 replaced the term dysplastic nevus with atypical mole Histologically it is termed nevus with architectural disorder Characteristically, these lesions share similar characteristics of melanoma May run in families as the FAMM Familial Atypical Mole and Melanoma Syndrome The presence of atypical moles significantly increases the chances that one may get a melanoma in their lifetime

Junctional Nevus
Dark brown macules representing a collection of nests of melanocytes at the dermo-epidermal junction Color uniform throughout Benign process Lesion should be observed for change in size, texture, color uniformity, border regularity

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Blue Nevus
Presents as well-defined, blue-black papule Common on dorsum of hands and feet Represents a melanocytic process deep in the dermis, causing different refraction of light clinically evident as blue color Benign, but does exist in a particularly virulent malignant form

Superficial Spreading Melanoma

Most common type of melanoma Grows slowly, usually within a pre-existing benign melanocytic process

Nodular Melanoma
Next most common type Often said not to have a radial growth phase that it starts out in the vertical growth phase Poorer prognosis as depth tends to be deeper

Acral Lentiginous Melanoma

Most common type in African-Americans Commonly affecting the soles, palms and toes, particularly the nail unit Can cause melanonychia, which is pigment in the nail plate Leakage of pigment proximally away from nail fold is called Hutchinsons sign and should be considered very foreboding Must be differentiated from normal pigmented linear bands in nails of African-Americans Often diagnosed at later stages and therefore has a poor prognosis Nail matrix biopsy is diagnostic

Lentigo Maligna Melanoma

Least frequent type Develops from lentigo maligna, the in-situ form of lentigo maligna melanoma Known to stay in radial growth phase for up to 40 years Most common on face and upper extremities

Common Features of All Melanomas

Usually greater than 6 mm. in greatest diameter before clinically evident as melanoma Lesions are asymmetrical you cannot bisect the lesion anywhere to make two mirror images Varied degree of pigmentation throughout the lesion with varying shades of tan to brown to black in early lesions; red, white, and blue in later lesions Irregular borders Elevation or enlargement

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General Principles Regarding Management of Melanoma

Excisional biopsy when possible is always preferred Incisional biopsy for large lesions is very much acceptable Shave or curettage biopsies are never appropriate Ulcerated lesions have a much poorer prognosis For biopsy surgery, only small margin of normal skin is required For definitive surgery, marginal tissue excision determined by depth from pathology report. In general, start with 3 cm margin, adding 1 cm more for each millimeter of depth Excision surgery should be oriented parallel to direction of lymphatic drainage Pigmented bands in nails must be biopsied at the matrix level

Prognostic Indicators for Melanoma

Clarks Levels of Invasion Clarks Levels of Invasion is a method of prognosticating based on visualization of tumor at certain depths. Level 3 and beyond is considered the point where significant risk of metastases begins. Described as Levels 1-5 as follows: 1. Confined to epidermis in situ 2. Extends beyond epidermis 1 mm into the papillary dermis 3. Extends to the junction of the papillary and reticular dermis 4. Extends into the reticular dermis 5. Extends into the subcutaneous fat

Breslows Tumor Thickness (Depth)

Breslows tumor thickness (depth) is a method of prognosticating based on actual depth in millimeters of extension into the skin starting at the granular layer using a measuring device in the eyepiece of the microscope called an ocular micrometer. Thought to be more reliable and reproducible than Clarks levels. .76 mm is the breakpoint after which the risk of metastasis rises sharply.

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