The Benign Common Acquired Nevomelanocytic Proliferations

70 Pages·2007·12.54 MB·English

THE NEVOMELANOCYTIC PROLIFERATION
The Benign Common Acquired
A. NEIL CROWSON Nevomelanocytic Proliferations
DIRECTOR OF DERMATOPATHOLOGY
UNIVERSITY OF OKLAHOMA
• Freckles and lentigines
PROFESSOR OF DERMATOLOGY and PATHOLOGY
• The mucosal and paramucosalmelanoses
CYNTHIA M. MAGRO
• The common acquired nevi :
DIRECTOR OF DERMATOPATHOLOGY
OHIO STATE UNIVERSITY –JunctionalNevus
PROFESSOR OF PATHOLOGY
–Compound Nevus
MARTIN C. MIHM
–Dermal Nevus
MASSACHUSETTS GENERAL HOSPITAL
HARVARD MEDICAL SCHOOL
PROFESSOR OF PATHOLOGY
The Benign Common Acquired Nevi :
Essential Characteristics
• Lentiginousand/or nested array within
epidermis
• Cellular constituents :
–Type A (epithelioid), type B (small
lymphocyte-like), type C (neuroidal)
• Pattern : symmetry of dermal and epidermal
components
• Maturation : progressive diminution of
nuclear size and evolution of cell type
(A⇒B ⇒C) Compound nevus: Lentiginousand nested
proliferation of bland appearing melanocytesalong the
dermal epidermal junction
Topic I:Freckles, Lentiginesand Melanoses
Dermal Nevus
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The Freckles and Lentigines
• Not classified as a form of precancerous
melanocyticproliferation
• Their recognition is important because : Multiple punctatelentigines
characterize LEOPARD
–Clinical appearance resembesmelanoma
syndrome
Peutz-Jeghers
–Multiple lentiginesmay be a sign of a
Syndrome: macules
systemic disease associated with non- on lips + buccal
melanocyticcancers. mucosa
CASE 1:
A 55 year old woman has an
irregular black macular lesion of the
introitusthat measures 3.0 x 2.5 cm
Diagnosis :
Vulvar Melanosis
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The Genital MelanocyticProliferations:
The Mucosal Lentigines
Main Forms
The Mucosal Lentiginesencompass:
(cid:131) Mucosal lentigo
• Labial melanoticmacule(lower lip; an
(cid:131) Vulvarmelanosis:
identical lesion is seen in the oropharynx)
(cid:131)With or without melanocytichyperplasia
• Genital Lentiginesup to 15 mm in diameter
(cid:131) Common acquired nevus
• Vulvar,urethral, oral + nasal melanosis:
(cid:131) Dysplasticnevus
multiple variably coalescing flat lesions
(cid:131) Malignant melanoma
resembling radial growth phase melanoma;
(cid:131) The prototypic genital nevus or atypical all may be melanoma precursors
melanocyticnevus of genital type
• Conjunctivalmelanosis
Vulvar Melanosis
• Clinical presentation: presents as a
solitary (up to or several centimeters in
size) or multiple intensely pigmented
macule(s); similar phenomenon on penis
is called penile melanosis.
• Clinical differential diagnosis: radial
growth phase mucosal LMM, patch type
bowenoidpapulosis, and pigmented
Bowen’s disease
Vulvar Melanosis :
Histomorphology
• Hypermelanosis
• Mild (cid:57)in basal layer melanocytenumbers
• Acanthosis
• No melanocyticatypia
• Differential diagnosis: atypical lentiginous
melanocytichyperplasia which is a precursor
lesion to melanoma
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Practice point: Uniform homogeneous
basilar pigmentation : A clue to benignancy
Penile Melanosis :
Differential Diagnosis
• The appearance of a periurethral
pigmented maculein mid to late life may
be the only sign of urethral melanoma
• Such patients require careful urological
examination and biopsy
Mucosal LentigoFromSimulators of Malignant Melanoma
Drs. Kerland Cerroni, University of Graz
Freckles : brown maculeson sun-exposed skin
The Freckles and Lentigines
• Freckles: light brown maculestypically less than 6
mm on sun exposed skin reflecting increased
melanizationdue to an increase in the functional
activity of the melanocyte
• Lentigines: pigmented maculeless than 1 cm in
diameter; typically oval, < 5mm.
• Café au laitmacules:
–Solitary lesions not uncommon
–>5 lesions >0.5cm strongly correlate with a
diagnosis of neurofibromatosis
–Manifest hypermelanosis, slight increase in
melanocytes, giant melanosomes(>2 um)
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Cafe au Laitmaculesin an adult
Cafe au Laitin a toddler
Practice point:
•Freckles disappear in winter and re-appear in summer.
•If these lip lesions did not show that behavior,
one would suspect Peutz-Jegherssyndrome
Cafe au Laitmaculein an 18 yr
Cafe au Laitin an infant
old with dysplasticnevi syndrome
Lentigines and Freckles
• Albright’s syndrome: basis is a postzygoticmutation of the
gene GNAS1 that encodes the alpha subunit of a signal
transducingheterotrimericguanine nucleotide binding
protein. The syndrome comprises:
–Polyostoticfibrous dysplasia,
–Melanoticmacules, and
–Hyperfunctionalendocrinopathy
• Sporadic mutation of the tyrosinasegene which is the
pathophysiologicbasis of the skin pigmentation
• Borders of the lesions are irregular
• Skin biopsies show hypermelanosis; there is no increase in
the number of melanocytes
Practice point: Any unusual pigmented lesion approaching
the natal cleft should prompt consideration of underlying
abnormalities of spinal cord or spine
Nevus Spilus
Nevus Spilus: Incipient junctionalnevus super-
imposed on a background of lentigosimplex
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Becker’s Nevus
Solar Lentigo
• Multiple maculeson sun damaged skin with
predilection for face and dorsa of hands
• Elongated retiato zones of atrophy, chronic
photoactivationof melanocytescan mimic
lentigomaligna
• Differential Diagnosis :
–Incipient lentigomaligna
–Superficial pigmented actinic keratosis
(SPAK)
Solar Lentigines
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EpithelioidPhotoactivation
Chronic Photoactivation
• The proliferation is lentiginous(i.esingly
disposed cells)
• Rarely confluent
• Nesting is not seen
• The cells have either an epithelioid
morphology or demonstrate nuclear
angulationand hyperchromasia(i.eso
called “lentiginous” cytomorphology)
Lentiginous
Photoactivation
CASE 2:
TOPIC II: THE DERMAL DENDRITIC A 27 year old man has a 12 x 12
MELANOCYTIC PROLIFERATION/ cm pigmented lesion with a dusky
DERMAL MELANOCYTOSIS bluish hue over the right cheek
and eyelid
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The Nevi of Ota and Ito
(cid:131) Clinical features
• Both are defined by a unilateral light gray Ota’s Nevus
maculepresenting in 1st-2nddecades, up to 5
cm diameter which darkens with age in :
•Trigeminal nerve distribution (1/2>3) (OTA, 1939)
•Acromioclavicularnerve distribution (ITO, 1954)
• Asiatics>African>Caucasians
• Darken as patient ages
The nevi of Ota and Ito
(cid:131) Histomorphology
• Band-like disposition of melanophagesand dendritic
melanocytesin the upper 1/3rd of the reticular dermis;
epidermis spared
Practice point: Scleralnevus of Ota is • Dendriticcells cytomorphologicallysimilar to those of
associated with choroidalnevi and blue nevus
melanoma; ophthalmic examination is • Cellularityis sparse and fibrosis is slight
required • Sclerallesions also involve nerves and may be more
cellular (Ota)
•Ota’s nevus may involve the tympanum and the
nasopalatineganglia
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The Dermal Melanocytoses
(cid:131) Nevi of Ota and Ito
(cid:131) Sun’s nevus
(cid:131) Dermal melanocytichamartoma
(cid:131) Mongolian spot
(cid:131) Blue nevus
(cid:131) Blue nevus with hypercellularity
(cid:131) Cellular blue nevus
Blue Nevus 2
The Blue Nevus
• The Blue nevus of Jadassohn-Tieche
• Mainly a lesion of childhood
• Most common location: dorsum of hands
and feet, less often the buttocks, head
and neck; can occur on mucosal surfaces Blue Nevus 3
• Typically 3 to 4 millimeters
• Can be multiple and inherited as an
autosomaldominant trait
Blue nevus in oral cavity
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EpithelioidBlue Nevus: Seen in 10% of Carney’s complex:
spotty pigmentation; cardiac, mammary + cutaneousmyxomas;
adrenal hyperplasia; Sertolicell tumor; pituitary adenoma
HypomelanoticBlue Nevus
Blue Nevus With Hypercellularity
• Clinically blue nevi often with a central
areas of hypopigmentationand/or firmness
with surrounding dense blue coloration
• Histologicallyhas blue nevus components
with cellular intradermalnidiof spindle cell
fascicles
Cellular fascicles of
spindle cells
surrounded by classic
blue nevus component
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