Melanoma

Melanoma

 

Evaluation/Diagnostic Protocol

Subjective:  Where—back of legs, back, anterior chest, feet, bottom of feet?  How Long—days, months, years?  Symptoms—pruritic, painful, bleed?  Quality—red, brown, black, pink, gray?  Severity—good/bad day?  Mod. Factors—hx of melanoma?  Context—associations, excessive sun exposure?  Family hx of melanoma?  Fair complexion? Red or blond hair, freckles, tendency to sunburn easily?  Presence of precursor lesions i.e., Clark’s dysplastic melanocytic nevus, congenital melanocytic nevus?

Risk Factors:

  • Genetic markers (i.e., CDKN2A mutations)
  • Family history of dysplastic nevi or melanoma
  • Ultraviolet irradiation
  • Sunburns during childhood
  • Intermittent burning exposure in unacclimatized fair skin
  • Number >50 and size >5mm of melanocytic nevi
  • Congenital nevi
  • Number of atypical nevi >5
  • Atypical/dysplastic nevus syndrome
  • Personal history of melanoma
  • High socioeconomic status
  • Skin type I, II: pale skin, poor tanning ability, light hair and eyes, presence of freckles, burns easily
  • Equatorial latitudes
  • DNA repair defects (i.e., xeroderma pigmentosum)
  • Immunosuppression

Objective:  Pigment variation of dark brown, black, pink, or gray; starts as flattened papule, progressing to plaques, and then nodule; Assess sun exposed areas of body: back, legs, anterior chest, back, anterior/posterior bilateral feet, toes, in-between toes, trunk

Lab: Biopsy, then proceed according to pathology report

Different types of Malignant Melanoma

  1. Superficial spreading melanoma (SSM)     
    1. Frequency:  60-70%
    2. Site:  any site, preference for lower extremities (females), trunk (males)
    3. Radial growth:  YES
    4. Special features:  more pagetoid, less solar elastosis

                                                              i.      Most common type of cutaneous melanoma in fair skinned individuals

                                                            ii.      Diagnosed most frequently between 30-50 years. 

                                                          iii.      Accounts for 70% of all melanomas

                                                          iv.      Most frequently seen on trunk of men and legs of women

                                                            v.      Begins as an asymptomatic brown to black macule with color variations and irregular notched borders

  1. Melanoma in situ
    1. Macule w/ irregular outline
    2. Variable size

                                                              i.      Diameters <5mm

    1. After typically slow horizontal (radial) growth phase limited to the epidermis or focally in the papillary dermis
    2. A rapid vertically oriented growth phase which presents clinically with development of papule or nodule can be frequently observed.
  1. 2/3 of cases show regression –visible as hypo/depigmentation of part of the lesion:  this is probably reflecting the interaction of the host immune system with progressing tumor. 
  2. 1/3 of melanomas arise in a pre-existing nevus
    1. a previously stable melanocytic nevus is generally observed to change
    2. becoming Asymmetric with an irregular Border
    3. Color variation
    4. enlarging Diameter
    5. ABCD mnemonic

                                                              i.      Asymmetry in shape

                                                            ii.      Border is irregular

                                                          iii.      Color is mottled

                                                          iv.      Diameter is usually large >6.0mm

                                                            v.      Elevation is almost present

                                                          vi.      Enlargement or a history or increase in size is perhaps the most important sign

  1. Nodular Melanoma
    1. Second most common type
    2. Frequency:  15-30%
    3. Site:  any site, preference for trunk, head, neck
    4. Radial growth: NO
    5. Special features:  nodule with vertical growth
    6. More in men than in women
    7. Presents as a BLUE to BLACK sometimes RED to SKIN colored nodule with might be ulcerated or bleeding and has rapidly developed over months
    8. Lacks significant macular hyperpigmentation and should not be confused with nodules occurring in superficial spreading melanoma
  2. Lentigo Maligna Melanoma:
    1. Frequency:  5-15%
    2. Site: face, especially nose and cheeks
    3. Radial growth: YES
    4. Special features: slower growth over years on sun-damaged skin
    5. Minority of cutaneous melanoma—up to 15%
    6. Diagnosed most frequently in 7th decade of life
    7. Occurs on chronically sun damaged skin
    8. Most common on face with a preference for the nose and cheek
    9. Develops as a slowly growing asymmetric brown to black macule with color variations and irregular, indented borders
    10. May develop a papule or nodule, generally indicating invasion
  3. Acral Lentiginous Melanoma
    1. Frequency:  5-10%
    2. Site:  palms, soles, subungual, in and around the nail apparatus
    3. Radial growth: YES
    4. Special features:  most common melanoma in patients with darker skin types
    5. Represents up to 70% of melanomas in dark complected persons
    6. 45% in Asians
    7. Is cumulatively more common in fair skinned patients BUT is the most common type found in pigmented races.
    8. Presents

                                                              i.      Asymmetric brown to black macule

                                                            ii.      + color variation

                                                          iii.      + irregular borders

                                                          iv.      Believed this type of melanoma is faster than LMM or SSM

    1. Diagnostically challenging

                                                              i.      May be mistaken for warts or SCC

                                                            ii.      Subungual melanoma accounts for 1-3% of all melanoma

1.      Typically classified as a variant of ALM

2.      present as longitudinal nail pigmentation or ulcerated nodules

3.      Persistence of pigmented band in nail bed, particularly in the elderly, should raise suspicion of melanoma and prompt biopsy.

4.      Any persistent pigmentation of the nail apparatus should raise concern for melanoma, realizing that benign causes are common

a.       Correct biopsy of nail matrix is important

b.      Extension of pigment into the proximal or lateral nail fold is known as a Hutchinson sign and generally indicates the presence of ALM

  1. Malignant Blue Nevus: Malignant Melanoma in Association with Blue Nevus
    1. Rare dermal tumor
    2. Melanocytes most commonly located on the head and particularly the scalp
    3. Appears blue-black, deeply situated nodule
    4. Generally >1cm in diameter
    5. Clinical course: high rate of recurrence and metastasis
  2. Desmoplastic/Spindled/Neurotropic Melanoma
    1. This type of melanoma is histologically defined
    2. Typical clinical lesion consists of

                                                              i.      Skin colored, red to hyperpigmented nodule or plaque, mostly on sun exposed skin

                                                            ii.      May arise de novo, but is also the most common melanoma arising in lentigo maligna, ALM, and mucosal melanoma

                                                          iii.      Metastasis is uncommon but the tumor is highly infiltrative and thus locally aggressive with recurrence after incomplete excision

                                                          iv.      Deep tissue samples are necessary to establish diagnosis 

  1. Clear Cell Sarcoma:  melanoma of soft parts
    1. Presents on distal extremities of adolescents and young adults
    2. Tumors arise in association with tendons and aponeuroses
  1. Ocular Melanoma
    1. Primary ocular melanomas, VERY RARE
    2. 5% of all melanomas
    3. can be divided into conjunctival melanomas and uveal melanomas (iris, choroidal, ciliary body melanomas)
    4. Little is known about pathogenesis of these tumors
    5. Patients with dysplastic nevus syndrome have increased number of conjunctival and uveal nevi
    6. True association between dysplastic nevus syndrome and ocular melanoma is controversial
    7. It is suggested that patients with ocular melanoma have increased risk for cutaneous melanoma
    8. Patients with type I neurofibromatosis and melanosis oculi (nevus of ota) may also be at higher risk for uveal melanoma
  1. Mucosal Melanoma
    1. Occur in mouth, nasopharynx, larynx, vagina, and anus

                                                              i.      Rare but tumors tend to be advanced

                                                            ii.      It is suggested secondary to early detection is difficult

Differential Diagnosis

  • Melanocytic lesions that simulate melanomas clinically &/or histopathologically
    • Acral nevi
    • Ancient nevi
    • Black nevi (hypermelanotic)
    • Blue nevi and variants
    • Combined nevi
    • Congenital nevi biopsied shortly after birth
    • Deep penetrating nevus
    • Dysplastic (Clark’s) nevi
    • Halo nevi
    • Hyperplasia of melanocytes in sun damaged skin or in the epidermis\
    • Melanocytic proliferation over some benign neoplasms
    • Longitudinal melanonychia
    • Melanosis of mucosal regions
    • Nevi exposed to UV radiation
    • Nevi in genital regions (including mil-line nevi and flexural nevi)
    • Nevus sur nevus: “nevus on nevus”
    • Pigmented streaks in melanoma scars
    • Proliferating nodules in giant congenital nevi in newborns
    • Recurrent (persistent) nevi
    • Reticulated (ink-spot) lentigo
    • Spitz nevi and variants
  • Non-Melanocytic Simulators of Melanoma
    • Paget’s disease
    • Extramammary Paget’s disease
    • Pigmented epidermotropic metastasis of breast carcinoma
    • Epidermotropic neuroendocrine carcinoma
    • Bowen’s disease (pagetoid or pigmented)
    • Pagetoid reticulosis
    • Clear-cell artifacts around keratinocytes
    • Complete regression of skin tumors other than malignant melanoma (i.e., lichen planus like keratosis, basal cell carcinoma)
    • Pigmented basal cell carcinoma
    • Pigmented actinic keratosis
    • Dermatofibroma
    • Serborrheic keratosis
    • Pigmented poroma and pigmented porocarcinoma
    • Pigmented pilomatricoma
    • Subungual hematoma
    • Black heel (hemorrhage in stratum corneum caused by trauma)
    • Pyogenic granuloma
    • Tinea nigra
    • Thrombosed hemangioma