Clinical Features:

• Peak incidence in the third decade; slight female predominance
• Most common on the extremities
• Presents as a small, symmetric, sharply demarcated, pigmented papule or nodule of acute onset
• The importance of recognizing this entity lies in the fact that it is often misdiagnosed as melanoma. 

Histologic Features:

• Junctional or compound nevus (with the junctional component often predominating)
• The lesion displays a symmetric configuration with fairly sharply demarcated lateral borders.
• The nevus cells are uniform spindle cells arranged in tightly packed fascicles, with relatively uniform spacing between the fascicles and with the cells often vertically oriented.
• The spindle cells tend to be narrower than those of classic Spitz nevus, and have nuclei smaller than or equal in size to keratinocyte nuclei and inconspicuous nucleoli.
• The nevus cells typically contain at least focall abundant coarse melanin pigment, in contrast to Spitz nevus.  The pigment may also be present within the keratinocytes and the papillary dermis.
• The nuclei of the nevus cells become smaller as one procedes deeper into the lesion (they "mature").
• Mitoses are often present in the junctional component, but are rare to absent in the dermal component.
• Pigmented spindle cell nevus and Spitz nevus exist along a spectrum, and one sometimes encounters lesions with features intermediate between the two entities.

Cases associated with this book:

Dermpedia Scottsdale 2011 Case: Suspected Pigmented Spindle Cell Nevus with Negative FISH
Author: Artur Zembowicz M.D. Ph.D.

Conference: Dr. Z's Consultations
Research Project :Flourescence in situ hybridization (FISH) in diagnosis of melanocytic proliferations

Pigmented spindle cell nevus
Author: Artur Zembowicz M.D. Ph.D.

Conference: Dermpedia Teaching Collection