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LIVE BLOG: Pigmented Lesions

In this live blog from the 11th Annual SDPA conference, Dr. Jason Smith lectures on Pigmented Lesions. Find some of the highlights below

Types Pigmented Lesions:

  • Solar Lentigo                       
  • Molluscum Contagiosum
  • Lentigo Simplex
  • Dermal Mucinosis
  • Café-au-lait macule           
  • Spitz Nevus
  • Blue Nevus           
  • Appendageal Tumors
  • Dermatofibroma           
  • Clear Cell Acanthoma
  • Kaposi sarcoma           
  • Large Cell Acanthoma
  • Pigmented BCC
  • Pigmented Actinic keratosis           
  • Congenital Nevomelanocytic Nevus
  • Other Lesions with Halo Phenomenon Pigmented Lesions
  • Mastocytoma           
  • Atypical Melanocytic Nevus
  • Seborrheic keratosis           
  • Melanoma
  • Epidermal Nevus           
  • Histiocytoma
  • Subungual hematoma
  • Flat Wart
  • Supernumerary nipple
  • Acrochordon
  • Pigmented Spindle Cell Nevus
  • Basal Cell Epithelioma
  • Spitz Nevus           
  • Neurofibroma
  • Sclerosing Hemangioma           
  • Mongolian spot
  • Pyogenic Granuloma
  • Blue Nevus
  • Dysplastic Nevus
  • Lichen Planus
  • Cutaneous Melanoma
  • Sarcoidosis
  • Nonpigmented Pink Lesions           
  • Psoriasis
  • Basal Cell Carcinoma
  • Angioma         
  • Fibrous Papule
  • Angiokeratoma
  • Verruca Vulgaris



Thomas Habif, MD

Why? SKs resemble so many other pigmented lesions

  • Seborrheic Keratosis
  • Warts
  • Dermatofibroma
  • Pigmented Basal Cell Carcinoma
  • Squamous Cell Carcinoma
  • Melanocytic Nevi
  • Congenital Nevi
  • Atypical Nevi
  • Melanoma

Seborrheic Keratosis

  • Benign epithelial neoplasms
  • Variable clinical appearances with widespread distribution
  • Variable size – most 0.5cm to 2 cm diameter
  • Varying shades of brown, black – sometimes gray, pink
  • Surface may be keratotic (verrucous) or smooth
  • Some lesions domed with visible “horn cysts”
  • Well-circumscribed – “stuck on” appearance
  • Frequently multiple – often numerous
  • Examine closely – can simulate melanoma
  • Found on all cutaneous surfaces except palms, soles, and lips

Seborrheic Keratosis Variants

  • Irritated seborrheic keratosis
  • Inflamed erythematous border – pruritus
  • May stimulate squamous cell carcinoma
  • Stucco keratosis
  • Multiple, small (< 5mm), flat, tan or light gray
  • Lower legs, ankles, dorsum of feet
  • Dermatosis papulosa nigra
  • Multiple, small (< 3 mm), domed or pedunculated
  • Diffuse facial papules – adult black patients

SKs: Instant Diagnosis

  • Primary Lesions
  • Color
  • Surface Characteristics
  • Distribution

Seborrheic Keratosis 2 types

  • 1. Rough Surface
  • Thick surface scale
  • Scale dries and cracks
  • Forms a uniform surface pattern
  • Seribraphorm appearance
  • Hypercharatotic appearance
  • 2. Smooth Surface   
  • Thin surface scale over a dome-shaped structure
  • Milia-like cysts on surface and deep in lesion

Histologically: Comedone-like plugs in adnecal openings

Irritated SK may Mimic from Melanoma

Leser-Trélat Sign

  • The sudden appearance of numerous (sometimes hundreds) of Seborrheic Keratoses
  • Can be associated with underlying malignancy, most commonly abdominal adenocarcinoma
  • One third of patients with this sign may also have acanthosis nigricans, another potential marker for internal malignancy


  • “Freckle” (vs. lentigo)
  • Light brown to medium brown macule usually less than 6 mm in diameter
  • Exposed areas of the face, shoulders, and outer aspect of the arms
  • Hyperpigmentation of the basal layer without elongation of the rete ridges (no increase in melanocytes)
  • Lentigos do not fade in the winter months

Solar Lentigo

  • A light to dark brown, even colored or reticulated macule occurring in sun-exposed areas
  • Can be solitary, they are more frequently multiple in occurrence
  • Dorsal aspects of the hands, extensor forearms, upper trunk, and face
  • Elongation of the rete ridges with a mild increase in the number of melanocytes


  • Macular hyperpigmentation
  • Increased epidermal melanocytes
  • Term used to describe melanocytic proliferation arranged as single cells and NOT as nests
  • Seen in:
  • Solar lentigo and lentigo simplex (children)
  • Lentiginous junctional and compound nevi
  • Lentiginous dysplastic nevi
  • Lentigo Maligna Melanoma

Peutz-Jeghers Syndrome

  • When you see lentigo on lips of children
  • Hamartomatous intestinal polyps
  • Usually benign
  • Adenocarcinoma reported
  • Endoscopic evaluation every 2-3 years




  • Nevocellular nevus
  • ‘Mole’


  • Junctional nevus: brown macule with melanocytic nests at the junction of the epidermis and dermis, usually flat, pigmented nail streak
  • Intradermal nevus: skin-colored or light brown papule with nests of melanocytes in the dermis, usually raised
  • Compound nevus: brown papule with combined histologic features of junctional and intradermal nevi

Blue Nevus

  • Localized proliferation of dermal melanocytes.
  • Typically small
  • Usually solitary, occurs on the head and neck. May be present since birth or infancy.
  • Generally less than 1 cm, range in color from dark blue to black with well-defined margins. Smooth surfaced with preservation of the skin lines.
  • The Tyndall Effect makes it blue
  • Tyndall phenomenon
  • Dermal pigmentation appears blue because of decrease reflectance in the longer-wavelength region compared with the surrounding area. Long wavelengths (red, orange and yellow) are not reflected and continue into deeper parts of the skin compared with the shorter-wavelength blue and violet, which are reflected to the skin surface

Congenital pigmented nevus has many other names:

  • Congenital nevomelanocytic nevus
  • Large congenital melanocytic nevi
  • Giant pigmented nevus
  • Giant hairy nevus
  • Bathing trunk nevus
  • Garment nevus

Congenital pigmented nevus –

What defines large or giant CMN?

  • Small congenital nevi are <1.5 cm in diameter (in adults)
  • Medium-sized congenital nevi are between 1.5 and 19.9 cm in diameter (in adults)
  • Large (or giant) congenital nevi  >20 cm in diameter (in adults)

Malignant potential?

–  The risk of melanoma arising within a small or medium-sized CMN is low (<1% over a lifetime) and is extremely low before puberty

–  Melanoma develops in approximately 5% of patients with a large CMN, with half of this risk in the first few years of life

–  Both melanoma and neurocutaneous melanocytosis are most likely in patients with CMN that have a projected adult size of >40 cm in diameter, many satellite nevi, and (especially for melanoma risk) a truncal location

What to tell parents?

Management of CMN requires education of patients and parents to reduce unnecessary anxiety and an individualized approach to monitoring and treatment that depends on the size, location, and clinical morphology of the nevus and psychosocial concerns of the family

++ Signature Nevi++

“The predominant group of nevi in an individual that share a similar clinical appearance”



“The common architecture and configuration of nevi in an individual that is consistent with their phenotype” –Smith

Cheetah Phenotype

  • Numerous small, darkly pigmented melanocytic nevi admixed with multiple solar lentigines

Halo Nevus

  • The mole on the inside has to look benign or else it needs a biopsy
  • Natural History: many will re-pigment and the nevus will disappear.  Some cases, the ring disappears and the nevus stays.

Spitz Nevus

  • Benign juvenile melanoma
  • Dome shaped pink nodule less that 1cm
  • Rx: Surgical incision

Management after Revealing Biopsies

  • If biopsy reveals mild dysplasia clinically the mole was completely removed by biopsy AND the path report reveals margins uninvolved THEN no further treatment is necessary
  • If the biopsy reveals moderate dysplasia OR worse THEN re-excise with at least 3 mm margins

Skin Cancer in USA – 2013 Data


  • 2,800,000 Basal Cell Carcinomas/ year
  • 700,000 Squamous Cell Carcinomas/ year (deaths)
  • How many new cases of Melanoma
  • –   76,690 Invasive Malignant Melanoma (9480 deaths)


Skin Cancer Deaths

–  12,650 Total

–  9,480 Malignant Melanoma 6,280 MM (Male)

–  3,200 MM (Female)

–  3,170 Non-Melanoma Skin Cancers


Life Time Risk of Melanoma

–  1/50 (All Melanomas)

–  ??? (All Invasive Melanomas)

–  1/35 (Male – Invasive Melanomas)

–  1/54 (Female – Invasive Melanomas)


++ Melanoma: Types and Differential Diagnoses++

Superficial Spreading Melanoma           

  • Dysplastic Nevi         
  • Basal Cell Carcinoma
  • Pigmented Bowen’s Disease
  • Solar Lentigo
  • Seborrheic Keratosis

Lentigo Maligna Melanoma

  • Seborrheic Keratosis
  • Pigmented Actinic Keratosis
  • Solar Lentigo         

Acral-Lentiginous Melanoma

  • Melanocytic Nevus
  • Verrucae
  • Kaposi’s Sarcoma
  • Pyogenic Granuloma
  • Eccrine Poroma
  • Trauma

Nodular Melanoma

  • Pyogenic Granuloma
  • Angiokeratoma
  • Kaposi’s Sarcoma
  • Metastatic Melanoma
  • Spitz Nevus
  • Pigmented Spindle Cell Nevus
  • Eccrine Poroma
  • Pigmented Basal Cell Carcinoma


Localized Disease; primary tumor ≤1.0mm thick. Localized Disease; primary tumor >1.0mm thick. Regional nodal disease or in transit metastasis. Disseminated Disease.

MM: Thickness, Invasion, & Ulceration

  • Breslow first described significance of tumor thickness, most important prognostic factor for all relevant outcomes.
  • Level of invasion is the most significant prognostic factor for thin lesions (<1.0mm), does not add prognostic info. to other thickness subgroups.
  • Tumor ulceration (absence of an intact epidermis) will add prognostic information, regardless of tumor thickness.


National Comprehensive Cancer Network is a great resource for Melanoma Guidelines

Common follow up recommendations for all patients according to NCCN

  • At least complete annual skin exam for life
  • Educate patient in monthly self skin exam –
  • Monthly self lymph node exam for Stage IA-IV
  • Routine blood tests are not recommended
  • Radiologic imaging is indicated to investigate specific signs or symptoms
  • Follow-up schedule influenced by risk of recurrence, prior primary melanoma, and family history of melanoma, and includes other factors such as atypical moles/dysplastic nevi, and patient/physician concern

Melanonychia Striata

What to Biopsy?

  1. Isolated pigmented band on a single digit that develops during the fourth to sixth decade of life
  2. Nail pigmentation that develops abrupts in a previously normal nail plate
  3. Pigmentation that suddenly becomes darker or larger or when the pigment becomes blurred near the nail matrix
  4. Acquired pigmentation of the thumb, index finger, or large toe
  5. Pigment that develops after a history of digital trauma and in which sublingual hematoma has been ruled out.
  6. Any acquired lesion in patients with a personal history of melanoma
  7. If the pigmentation is associated with nail dystrophy including partial nail destruction or absence of the nail plate
  8. If pigmentation of the periungual skin (including lateral nail folds) is found to be present (Hutchinson’s sign). This includes pigment of the cuticle or hyponychium


Image: Darren Hester

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