Spitz (Spindle and Epithelioid Cell) Nevi

 Spindle cells much more common


image Epithelioid cells usually dispersed individually throughout lesion


• Melanocytes “mature” by becoming smaller from superficial to deep

• Kamino bodies: Eosinophilic globules at dermal-epidermal junction

• Artifactual clefting of papillary dermal nests from overlying epidermis often present

• Can show atypical features (atypical Spitz nevus/tumor)
image Pleomorphic cells with large, irregular nuclei and prominent eosinophilic nucleoli

image Increased mitoses may be seen

• Variants: Halo Spitz nevus, desmoplastic Spitz nevus




Top Differential Diagnoses




• Spitzoid melanoma; findings suspicious for melanoma include
image Patients usually > 10 years old

image Lesions usually > 1 cm

image Ulceration and increased mitoses often present

image Asymmetry and poor circumscription

image Subcutaneous involvement

• Pigmented spindle cell nevus of Reed (usually leg of young adult female)

• Conventional melanocytic nevi

image
Clinical Photograph of Spitz Nevus
A small, symmetric pink papule, typical of a Spitz nevus, is shown on the face of a child. (Courtesy R. J. Antaya, MD.)


image
Classic Spitz Nevus
Histologic examination of a classic Spitz nevus shows nests of spindled and epithelioid-shaped melanocytes at the dermal-epidermal junction and in the dermis. Note the clefting artifact overlying several of the nests image.

image
Spitz Nevus at High Magnification
High-power examination of a Spitz nevus shows small nests of epithelioid to spindled melanocytes with overlying artifactual clefting image and an eosinophilic Kamino body image.

image
Kamino Body in Spitz Nevus
High-power examination of this case shows a small, densely eosinophilic-staining Kamino body image, which is an eosinophilic globule found at the dermal-epidermal junction. These are typical of Spitz nevi but are not seen in most cases.


TERMINOLOGY


Synonyms




• Spindle and epithelioid cell nevus

• Spindle cell nevus

• Epithelioid cell nevus

• Nevus of large spindle &/or epithelioid cells

• Benign juvenile melanoma (outdated term)


CLINICAL ISSUES


Site




• Trunk

• Head and neck

• Extremities, especially thigh


Presentation




• Most common in children and young adults
image 0.5-1.0% of all nevi in children and adolescents

image May occur at all ages

• Solitary
image Can be clustered or disseminated


Treatment




• Complete conservative excision


Prognosis




• Benign tumors; only very rare malignant transformation

• Low recurrence rate, even after incomplete excision


MACROSCOPIC


General Features




• Dome-shaped dermal nodule

• Pink or flesh colored

• Often misdiagnosed clinically as hemangioma or pyogenic granuloma


Size




• Usually < 1 cm


MICROSCOPIC


Histologic Features




• Junctional, compound, and dermal forms
image Most common type is compound with prominent dermal component

• Symmetric, well-circumscribed proliferation
image Usually no lateral extension of junctional nests beyond dermal component

• Varying proportions of spindled and epithelioid melanocytes
image Spindle cells more common in most cases
– Completely spindle cells in ~ 45% of Spitz nevi

– Mixed spindle and epithelioid cells in ~ 35%

– Only epithelioid cells in ~ 20%

image Epithelioid cells usually dispersed individually throughout lesion

• Spindle cells are arranged in fascicles perpendicular to epidermis

• Small clusters of melanocytes can be seen in epidermis
image Can see pagetoid spread of few single melanocytes

• Artifactual clefting of junctional nests from overlying epidermis

• Kamino bodies
image Eosinophilic globules at dermal-epidermal junction

image Important diagnostic clue, but not always seen (may need step sections to find)

image PAS(+) and trichrome (+)

• Melanocytes show “maturation” as they become smaller from superficial to deep
image Melanocytes often taper to narrower areas in deep dermis, forming upside-down triangle

Only gold members can continue reading. Log In or Register to continue

Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Spitz (Spindle and Epithelioid Cell) Nevi
Premium Wordpress Themes by UFO Themes
%d bloggers like this: