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Spitz Nevus - Submitted on: Sunday April, 15, 2007
Contributed by:Jeffrey A. Conklin, M.D. ,
Spitz nevus is of particular importance because of its diagnostic challenge.

Definition:
Spitz nevus was first described by Sophie Spitz in 1948 as a benign juvenile melanoma, which despite some histological similarities to melanoma behaved in a benign clinical course (1). It has also been called spindle cell nevus, epithelioid cell nevus, nevus of large spindle and/or epithelioid cells.

Clinical Features:
It is characterized by a solitary flesh or pink dome-shaped papule or nodule arising on the face, trunk or extremities, usually before puberty. Usually, Spitz nevi are small and in 95% of patients, the size is less than 1cm (2). The lesion is often lack of melanin pigment and is often vascular; therefore it may be clinically mistaken for a pyogenic granuloma or angioma. Variants include pigmented lesions, keloid-like type, congenital onset and multiple clustered lesions (agminated).

Histology:
Figures
(Click on an image for a larger view)
Figure 1. Spitz nevus is a small symmetrical well circumscribed lesion (Hematoxylin and Eosin, 4x).
Figure 2. This junctional Spitz nevus consists of vertically oriented nests (Hematoxylin and Eosin, 10x).
Figure 3. High power view shows large cells with abundant cytoplasm, open chromatin and prominent nucleoli (Hematoxylin and Eosin, 40x).
Architecturally, typical Spitz nevi are symmetric and have wedge-shaped outline with sharp lateral borders (Fig1). They are usually compound with a prominent intraepidermal component, but can be intradermal or junctional. They are often accompanied by other changes such as epidermal hyperplasia with hyperkeratosis, parakeratosis, patchy perivascular lymphohistiocytic inflammation and papillary dermal vascular ectasia. The junctional component of Spitz nevus is arranged in nests with vertical orientation. The nests are large but should not vary greatly in size or shape or become confluent (Fig2). Architectural features favoring malignancy include: size greater than 6mm, asymmetry, intraepidermal component extending beyond the dermal component, lack of vertical orientation of nests and the presence of confluent spread.

The nests of Spitz nevi are composed of large spindle or epitheliod cells, or both. The cells are large with ample cytoplasm and prominent eosinophilic nucleoli (Fig3). Cellular maturation should be present with increasing depth. The cells towards the base of the lesion should be small and look similar. Bizarre giant cells may be present in Spitz nevus. The nuclei should be of similar size in Spitz nevus versus the pleomorphic nuclei of the bizarre giant cells seen in some melanomas. Mitoses may be seen, however they should not be atypical or deep. Cytological features favoring malignancy include: fine dusky cytoplasm, abnormal mitoses and papillary mitoses, pagetoid spread, cellular pleomorphism and nuclear hyperchromatism.

Kamino bodies are eosinophilic hyaline globules with scalloped borders commonly located at the dermoepidermal junction and are seen in 60-80% of cases of Spitz nevi (3). Kamino bodies are composed of laminin, type IV collagen and fibronectin. Kamino bodies are less common in melanoma.


Treatment:
Complete excision is often advised especially given the difficulty differentiating Spitz nevus from melanoma. Spitz nevi are benign but may recur if incompletely excised.

Bibliography:
  • 1. Spitz S. Melanomas of childhood. Am J Pathol 1948; 24: 591-609
  • 2. Weedon D, Little JH. Spindle and epithelioid cell nevi in children and adults. A review of 211 cases of Spitz nevus. Cancer 1977; 40: 217-225
  • 3. Kamino H, Flotte TJ, Misheloff et al. Eosinophilic globules in the Spitz nevus. J Am Acad Dermatol 1982; 7: 324-327.
     

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