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Skin-Melanocytic tumors
Spitz nevus
Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.
Revised: 26 October 2009, last major update June 2009
See also Atypical Spitz Nevus, Desmoplastic Spitz Nevus
Definition
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● Benign tumor of spindle and epithelioid cells
Terminology
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● Also called spindle and epithelioid cell nevus, benign juvenile melanoma
● First described by Sophie Spitz in 1948 (AJSP 1948;24:591)
Epidemiology
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● Usually occurs before puberty, but 2/3 at age 20+ years in one study (Am J Dermatopathol 2005;27:469)
Clinical
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● Usually single, but may also be multiple and clustered (agminate) or multiple and disseminated
● Benign, but may recur if incompletely excised or even if “clinically removed” (AJSP 2002;26:654)
● May involve regional lymph nodes, particularly in atypical lesions (AJSP 2002;26:47)
● Misdiagnosis of melanoma as Spitz nevus is common cause of malpractice claims (Archives 2006;130:617)
Sites
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● Trunk most common
● Lower extremities, head and neck
● Tongue lesions may have pseudoepitheliomatous hyperplasia and resemble malignancy (AJSP 2002;26:774)
Case reports
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● 2 year old boy with multiple clustered lesions on a pigmented macule (Actas Dermosifiliogr 2008;99:69)
● 23 year old woman with buccal lesion that metastasized (Melanoma Res 2008;18:36)
● 28 year old man with conjunctival tumor (Bull Soc Belge Ophtalmol 2007;303:63)
● 32 year old woman with lip lesion (Clinics 2008;63:140)
● Multiple agminate nevi (Melanoma Res 1998;8:156)
Treatment and prognosis
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● Complete excision for full histopathologic examination with evaluation of margins
● Clinical followup, particularly of multiple or atypical lesions
Clinical description
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● Small, raised, pink/red or brown/black nodule
● May resemble hemangioma or pyogenic granuloma
● Usually 6 mm or smaller
Clinical images
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Small, symmetrical, pink-tan 11-year-old boy with arm lesion
lesion
Various images Macule in the form of a quadrant with brown papules
of various hues within its margins (Figs 1, 2)
Micro description
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● Symmetric with sharp lateral borders, usually compound nevus with prominent intraepidermal component
● 5% are junctional, 20% are dermal
● Composed of spindle cells and epithelioid cells
● Spindle cells may be arranged in fascicles in the dermal papillae, perpendicular to epidermis, are cigar shaped with large nuclei and prominent nucleoli
● Epithelioid cells are dispersed individually, are polygonal with abundant eosinophilic cytoplasm, distinct cell borders, large nuclei and prominent nucleoli, variable mitotic figures, occasional multinucleation, often marked atypia, although most cells appear benign
● Cell maturation occurs in deep portion of tumor
● Also large and well formed Kamino bodies (eosinophilic hyaline bodies along dermoepidermal junction)
● May have pagetoid growth, lymphatic invasion, pseudoepitheliomatous hyperplasia, “tubular” growth pattern, plexiform growth pattern, halo reaction, prominent vasculature (Am J Dermatopathol 2000;22:135), lymphocytic infiltrate
● Scanty pigmentation
● “Consumption of epidermis” (usually associated with melanoma) is seen in 10% of Spitz nevi, defined as thinning of epidermis with attenuation of basal and suprabasal layers and loss of rete ridges in areas of direct contact with neoplastic melanocytes (AJSP 2004;28:1621)
Micro images
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AFIP images
Bilaterally symmetric lesion has uniform hyperkeratosis with hypergranulosis, fairly uniformly elongated rete ridges and a proliferation of melanocytes in the epidermis that "rain down" through the papillary dermis into the reticular dermis as attenuated spindle cells
Bilaterally symmetrical lesion (fig A), has lateral cells arranged in nests (fig B), indicating that the lesion is well circumscribed; "transepidermal elimination" (fig C) does not indicate pagetoid spread; dermal lesional cells show imperfect but definite maturation, with attenuated single cells at the base of the lesion (fig D)
Pink eosinophilic globoid Kamino bodies are probably apoptotic cells
Melanocytes extend focally into epidermis, mostly as nests; the maturation into the dermis, globoid bodies in epidermis and characteristic cell type are attributes of Spitz nevus, not melanoma
Giant cells are commonly seen in Spitz nevi (fig A), as are the large intranuclear cytoplasmic invaginations that may also be seen in melanomas (fig B)
Maturation from large epithelioid cells to small nevus cells from superficial to deep within a Spitz nevus is an extremely important diagnostic feature, as is the permeation of reticular dermis by attenuated single cells at the base (fig B); mitotic figures (fig A), if not numerous and especially when entirely superficial, are not indicative of melanoma
Lip lesion-superficial nests of nevus cells Cells demonstrate pleomorphism,
with spread of cells in deeper areas hyperchromatism and multinucleation
Various images
Limited Ki-67 staining Strong S100A6 staining
Comparison with Melanoma
Spitz nevus (top) is well circumscribed and symmetric Spitz nevus (Fig a-h)
with nevus cell maturation, metastatic melanoma compared to spitzoid
(bottom) has similar features but no maturation melanoma (fig i)
Contributed by Angel Fernandez-Flores, MD, PhD, Hospital El Bierzo and Clinica Ponferrada, Spain
Other images: symmetric circumscribed lesion; nests of tumor cells with Kamino bodies #1; #2; nests of spindle cells; nests of epithelioid cells #1; #2; multinucleated cells; junctional; intradermal #1; #2; compound #1; #2; trunk #1; #2
Positive stains
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● S100, HMB45, Mart-1
● p16 (positive in nevus and negative in melanoma),
● WT1 (positive in melanoma and some dysplastic nevi, negative in other benign nevi, Histopathology 2007;51:605)
● Kamino bodies are PAS+ (even after predigestion with diastase)
● S100A6 (Mod Path 2003;16:505)
Negative stains
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● Low Ki-67 (J Am Acad Dermatol 2007;56:815, AJCP 2004;122:499)
● EMA, keratin, myogenic markers
● Usually CD99 (J Cutan Pathol 2007;34:576)
Molecular / cytogenetics
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● H-RAS occasionally but usually not N-RAS or B-RAF mutations, unlike melanoma (AJSP 2005;29:1145), but B-RAF mutations found in some classic and atypical Spitz nevi in another study (Mod Path 2006;19:1324)
Videos
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Differential Diagnoses
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● Melanoma - asymmetric, irregular lateral borders, uneven base, pagetoid scatter of melanocytes, uneven nests of melanocytes, lack of maturation, spindle cells not perpendicular to surface, epidermal spread, ulcerated surface, most cells appear malignant
Additional references
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● Mod Path 2006;19 Suppl 2:S21, eMedicine
End of Skin-Melanocytic Tumors > Spitz nevus
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