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.

The spitzoid malignant melanoma (SM) shows, depending on the type, characteristics of the Spitz nevus (NS) in different degrees. The diagnosis "melanoma" is made by a number of different significant, mainly histological features.

• SM: asymmetry of the tumour, NS: symmetry of the tumour
• SM: blurred lateral border (this is not true for a smaller part of spitzoid malignant melanomas), NS: sharp lateral border
• NS: irregular epidermal hyperplasia; SM: surface epithelium may be diluted over the tumor parenchyma.
• SM: melanocytes penetrate all layers of the epidermis, individually and in nests, and are located at irregular intervals from each other
• SM: Melanocytes, either individually or in nests, also penetrate the pelvic epithelia (infiltrative growth. SN: This characteristic is not found in the Spitz nevus)
• SM/NS: Pagetoid epidermal infiltration is untypical for the Spitz nevus. In spitzoid malignant melanoma this can be observed in about 20% of cases.
• SM: Melanocyte nests are of different size and configuration (signs of malignancy)
• SM/NS: Clefts between elongated melanocyte nests and the surrounding epidermis (usually identical)
• SM: Clefts between the dermal melanocyte nests are detectable throughout 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. Adnexae have completely disappeared.
• SM/NS: Typical cytological features are clearly enlarged melanocytes with large oval, round or polygonal nuclei and strongly developed cytoplasm. If this cell type is present throughout the entire tumor parenchyma, this type is called "uniform spitzoid malignant melanoma".
• SM/NS: Multinucleated melanocytes (mostly identical)
• SM/NS: Kamino-bodies are missing in SM, they are characteristic for NS.
• SM/NS: Pigmentation in both the pointed nevus and the spitzoid malignant melanoma is usually slight or absent. If present, spitzoid malignant melanoma shows an irregular distribution of melanin in the tumor parenchyma. If the parenchyma is clearly pigmented, a "pigmented spitzoid malignant melanoma" can be distinguished.
• SM: Detection of numerous mitoses in melanocytes both subepidermally and at the base of the tumour (mitoses in Spitz's nerve are rare).
• SM: lack of maturation of melanocytes at the base of the tumour (no decrease in cell and nucleus 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