Melanoma spitzoides C43.L

Spitz, 1948

See below histology

Age: 15 - 56 years, average: 35 years, w:m = 3:1

Extremities, trunk,

The spitzoid malignant melanoma is clinically described as red, less frequently than brown, flatly raised, 0.4-1.5 cm diameter, asymmetrical, firm papule/nodules with a smooth, mostly intact, rarely ulcerated and therefore bleeding surface.

Growth or also "organ sensation" or itching lead to the doctor. Frequently the diagnosis also turns out to be a chance finding. In 30% of cases polyposis (polypoides spitzoides malignant melanoma) can also be found.

Depending on the type, spitzoid malignant melanoma (SM) shows varying degrees of Spitz nevus (NS) characteristics. The diagnosis "melanoma" is made on the basis of a number of differently significant, mainly histological features.

• SM: Asymmetry of the tumor, NS: Symmetry of the tumor
• SM: Blurred lateral border (this does not apply to a small proportion of spitzoid malignant melanomas), NS: Sharp lateral border
• NS: Irregular epidermal hyperplasia; SM: Surface epithelium may be thinned over the tumor parenchyma.
• SM: Melanocytes permeate all layers of the epidermis individually and in nests and are irregularly spaced.
• SM: Melanocytes also penetrate the adnexal epithelia individually or in nests (infiltrative growth). SN: This feature is not found in Spitz nevus)
• SM/NS: Pagetoid epidermal infiltration is atypical for Spitz nevus. In spitzoid malignant melanoma this can be observed in about 20% of cases.
• SM: Melanocyte nests vary in size and configuration (sign of malignancy)
• SM/NS: Clefts between elongated melanocyte nests and the surrounding epidermis (usually identical)
• SM: Clefts between the dermal melanocyte nests are detectable through the entire tumor parenchyma (sign of malignancy; typical for the so-called "packed" spitzoid malignant melanoma)
• SM: The uniform spitzoid malignant melanoma is characterized by a compact tumor penetration of the dermis. Adnexa have completely disappeared.
• SM/NS: Cytologically typical features are markedly enlarged melanocytes with large oval, round or even polygonal nuclei and strongly developed cytoplasm. If this cell type is present throughout the entire tumor parenchyma, this type is referred to as "uniform spitzoid malignant melanoma".
• SM/NS: Multinucleated melanocytes (usually identical)
• SM/NS: Kamino-bodies are absent in SM, but are characteristic of NS.
• SM/NS: Pigmentation is usually slight or absent in both Spitz nevus and spitzoid malignant melanoma. If present, spitzoid malignant melanoma shows an irregular distribution of melanin in the tumor parenchyma. If there is clear pigmentation of the parenchyma, a "pigmented spitzoid malignant melanoma" can be differentiated.
• SM: Detection of numerous mitoses in melanocytes both subepidermally and at the base of the tumor (mitoses are rare in Spitz disease).
• SM: Lack of maturation of the melanocytes towards the base of the tumor (no decrease in cell and nuclear size). Remark: Important differential diagnostic feature!

S.u. Melanoma malignes

The malignant potential of "spitzoid" malignant melanomas seems to be different from that of other malignant melanomas. Spitzoid malignant melanomas show a relatively slow progressive course during childhood. In a larger study with 18 cases the sentinel LK was only positive once. 1x death due to metastasis occurred.

Epithelioid Spitz tumors (Spitz naevi, atypical Spitz tumors, spitzoid malignant melanomas show a loss of the BAP1 gene as well as B-RAF mutations independent of their dignity.

1. Allen A (1949) A reorientation of the histogenesis and clinical significance of cutaneous nevi and melanomas. Cancer 2: 28-56 (1949)
2. Allen AC, Spitz S (1953). Malignant Melanoma: a clinicopathological analysis of the criteria for diagnosis and prognosis. Cancer 6: 1-45
3. Breslow A (1970) Thickness, cross-sectional areas and depth of invasion in the prognosis of cutaneous melanoma. Ann Surg 172: 902-908
4. Requena C et al (2012) Characteristics of spitzoid melanoma and clues for differential diagnosis with acute nevus. At J Dermatopathol 34: 478-486
5. Spitz S (1948) Melanomas in childhood. Am J Pathol 24: 591-609
6. Wiesner T et al(2015) Morphological and genetic aspects of Spitz tumors Pathologist PMID: 25613920