Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st Year, 2nd Year, 3rd Year and Final year Surgery 18 Disorders of Melanocytes PPT-Powerpoint Presentations and lecture notes
Disorders of Melanocytes
Melanoma
Nevus
Histopathology:
Main cell is nevus cell
These are large ovoid cells with vesiculated nuclei, and pale cytoplasm
They are derived from neural crest cells
Congenital nevi
Rarer , 1% of neonates
larger and may contain hair
Congenital giant lesions (giant hairy nevus) most often occur in a bathing
trunk distribution or on the chest and back
Develop malignant melanoma in 1 to 5% of the cases
Excision of the nevus is the treatment of choice
Giant cel nevus
Acquired melanocytic nevi
Classified as junctional, compound, or dermal, depending on the location of the nevus cells.
Nevus cells accumulate in the epidermis (junctional), migrate partially into the dermis (compound), and
finally rest completely in the dermis (dermal).
Eventually most lesions undergo involution.
Melanocytes in Normal epithelium
Compound Nevus
- Shows junctional activity & nests
of nevus cells in connective
tissue.
Dysplastic Nevus
Multicolored
Asymmetric pigment
deposition
Asymmetric contour-macular
and papular
Indistinct margins
Atypical mole syndrome-(Dysplastic nevus
syndrome)
>100 melanocytic nevi
1 or more nevi >8mm in
diameter
1 or more dysplastic nevi on
exam
10 year risk of developing melanoma of 14%
Management
Close monitoring- full body exams every 6 months
Dermoscopy of all atypical appearing nevi
The magnified visualization of pigmented skin lesions beyond what would be visible by
the physician
Increases diagnostic accuracy by 10-20%
Excision of any changing or markedly atypical nevi
Melanoma
Melanoma: Pathogenesis
?
Cell of origin: melanocyte
?
Etiology:
? Cumulative and prolonged UVB and/or UVA exposure
? UVA exposure from tanning beds increases risk for melanoma
Risk Factors
? Individual risk factors for development of melanoma
? Increasing age
? Fair skin; blue eyes, red or blond hair; freckling
? Greater than 100 acquired nevi
? Atypical nevi
? Immunosuppression
? Personal or family history of melanoma (two or more 1st degree relatives)
? Ultraviolet exposure: Risk directly related to # of severe blistering sunburns
before puberty; tanning booth use
? Genetic syndromes
Heredity of Melanoma
? 10 % of melanomas are familial and have a genetic basis
? The genes CDKN2A and CDK4 together make up 50% of all
inherited familial cases
? Other identified genes include p53, BRCA2
? 50% of familial melanoma patients have no identified mutation ?
i.e., their genes have not been identified yet
Clinical Manifestations
? May cause symptoms, but usually asymptomatic
? May develop de novo or arise within a pre-existing nevus
? Majority located in sun-exposed areas, but also occur in non-sun-exposed
areas, such as the buttock
? Also occur on mucous membranes (mouth, genitalia)
? Typically appears as a pigmented papule, plaque or nodule.
? Demonstrates any of the ABCDEs
? It may bleed, be eroded or crusted
? Patients may give history of change
The ABCDEs of Melanoma
Suspicious moles may have any of the following features:
ASYMMETRY
? With regard to shape or color
BORDER
? Irregular or notched
COLOR
? Very dark or variegated colors
? Blue, Black, Brown, Red, Pink, White
DIAMETER
? >6 mm, or "larger than a pencil eraser"
? Diameter that is rapidly changing
EVOLVING
? Evolution or change in any of the ABCD features
Superficial Spreading
17
? Superficial spreading type
? Most common type
? Involves back in men; back and
legs in women
? Growth of tumor is primarily
horizontal rather than down into the
dermis
Nodular
18
? Nodular type
? Rapid growth
? Growth is vertical, giving tumor an
increased Breslow's depth
? Breslow's depth = thickness of the primary
melanoma measured from the granular
layer of the epidermis to the deepest part of
the tumor
Lentigo Maligna
19
? Lentigo maligna type
? Occurs on chronically sun-damaged
skin, more common in elderly
patients
? Slow progression
? Growth of tumor is primarily
horizontal, and not vertical
Acral Lentiginous
20
? Acral lentiginous type
? More common in people with darker
skin color (Asians and persons of
African ancestry)
? Diagnosis is often delayed, so
lesions tend to be many centimeters
in diameter
Amelanotic
21
? Amelanotic type
? Morphologic appearance is variable, and the clinical
appearance of pigment is subtle or often absent
? As such, the lesion may be confused with a variety of
benign lesions, such as psoriasis or dermatitis
? This lesion may also be confused with a variety of
malignant lesions, such as squamous cel carcinoma in
situ or basal cel carcinoma
? This is a difficult diagnosis to make, which is why it is
important to biopsy when unsure of the diagnosis
Diagnosis
Biopsy
Excision (Golden standard)
*ncision biopsy
*Punch biopsy
Partial thickness or shaving biopsies are contraindicated
*All dermis layers should be removed
Balch CM, Houghton AN, Sober AJ, Soong S.
Cutaneous Melanoma. St Louis QMP 1998
Staging (AJCC 7th Edition)
Clark Classification
Level I -- the atypical melanocytes are confined to the epidermis (in situ melanoma);
Level II -- the atypical melanocytes have extended into the papil ary dermis but have not
reached the reticular dermis;
Level III -- the atypical melanocytes have penetrated to the interface between the papil ary
dermis and the reticular dermis but do not extend into the reticular dermis;
Level IV -- the atypical melanocytes have extended into the reticular dermis;
Level V -- the atypical melanocytes have reached into the subcutaneous fat.
The histopathologic classification of the Melanoma by Clark
Breslow Classification
Level 1: less than 0.76 mm thick
Level 2: between 0.76? 1.50 mm
Level 3: between 1.50 - 4.00 mm
Level 4: exceed 4.00 mm in thickness
According to the thickness of the lesion as measured by an ocular micrometer from the top of
the granular zone of the epidermis to the base of the neoplasm
Prognostic Factors
n Breslow thickness (most important)
n Clark invasion level
n Ulceration
n Age, sex, location
n Size and surgical margins
n Others (Mitotic index, growth phase, regression.. )
Surgical Treatment
n Biopsy
n Wide Local Excision
n Staging with Sentinel Lymph Node biopsy
n Therapeutic Lymph Node Dissection
n Treatment of Distant Metastasis
Wide Surgical Excision
Suggested surgical margins:
(according to breslow thickness)
In-situ MM:
0.5-1 cm
Breslow thickness < 1mm : 1 cm
Breslow thickness 1-4 mm: 2 cm
Breslow thickness >4 mm: > 3 cm
Sentinel Lymphadenectomy
Sentinel Lymphadenectomy
Sentinel lymph node shows the regional node status
If sentinel lymph node negative, others lymph nodes in the basin are also
negative
If sentinel lymph node contains tumor cel s, It means disease spread to the
regional nodal basin
Sentinel Lymphadenectomy
Sentinel node negative
no additional treatment, follow the patient
Sentinel lymph node positive
Therapeutic lymph node dissection
Advantages of Sentinel Lymphadenectomy
n Provides staging
n Prevention of Elective Lymph node dissection morbidity
Sites of Distant Metastasis
n Skin
n Subcutaneous Tissue
n Distant Lymph Nodes
n Pulmonary
n Liver
n Brain
n Bone
n Intestine
Chemotherapeutic agents
? Melphalan
? Interferon
? Interleukin-2
? Dacarbazine
This post was last modified on 08 April 2022