malgnant melanoma from a child, initial specimen

MALIGNANT MELANOMA FROM A CHILD, INITIAL BIOPSY SPECIMEN

POSSIBLE 'MALIGNANT SPITZ NEVUS' OR MINIMAL DEVIATION

MELANOMA HAVING FEATURES OF A SPITZ NEVUS

This eleven year old female developed this lesion on her right leg. Her mother had a melanoma, but a detailed family history is not available.

Malignant melanomas in this age group are distinctly uncommon, and the dermatopathologist will, for good reason, bend over backwards to avoid the diagnosis. Many of the atypical melanocytic lesions in this age group are Spitz' tumors ('spindle cell nevi'). It should also be noted that there have been cases reported as malignant Spitz nevi or minimal deviation melanomas have the features of a Sptiz nevus with involvement of regional lymph nodes that have had an unexpectedly benign outcome.

The diagnosis of malignant melanoma was unavoidable in this case. The expansile mass, which is composed of cytologically malignant epithelioid cells (and few spindle cells) that have no appreciable intervening stroma, is different from the spaced fascicles of a Spitz' tumor. This paucity of stroma between cells and nests of cells also differs from the pattern found in combined nevi that have an epithelioid cell component and/or a component of plump spindle cells. The prominent lentiginous component that is seen in the edges of the biopsy is made up of large atypical cells, and such a component is not characteristic of a Spitz' tumor. Large pagetoid melanocytes may be found in Spitz' tumors or in some acral nevi, but they are cause for concern considering the other features of this case. The architecture of the lesion is not that of a wedge as is seen in some Spitz' tumors, ordinary or atypical. This tumor has some of the features of a minimal deviation melanoma with the features of a Sptiz' tumor, but that would be the subject of another discussion. The intradermal component that is peripheral to the expansile mass is atypical, and the significance of this is problematical. Melanomas may develop in patients who are younger than expected in the familal melanoma setting.

Scan power view. The expansile component of the tumor is delineated by the black line. Note the curved rete ridges near the edges of the expansile mass, indicative of an acquired lesion with fairly rapid growth.

Higher power of the extreme right side of the biopsy. Note the edge of the expansile mass in the upper left side of the picture. The cells differ from those found peripheral to the mass, but these cells are slightly atypical. Note the atypical lentiginous component.

From the left side of the biopsy, peripheral to the expansile mass. There are large, atypical cells in a lentiginous distribution and these are also forming nests at the junction. Keratinocyte hypertrophy is present (can be seen in Spitz' tumors and in melanomas).

Base of the expansile mass.

Interior of the expansile mass. Spindle and epithelioid cells are not associated with much stroma.

One of several mitoses within the expansile mass. A few mitoses were abnormal, as was this one. There is a peculiar regional cytoplasmic variation in the coloration of the large tumor cells that is not often seen in benign melanocytic lesions.

Small clusters of large cells and a large single cell in a pageoid distribution. There were not many of these. Keratinocyte hypertrophy is also present.

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	Scan power view. The expansile component of the tumor is delineated by the black line. Note the curved rete ridges near the edges of the expansile mass, indicative of an acquired lesion with fairly rapid growth.
	Higher power of the extreme right side of the biopsy. Note the edge of the expansile mass in the upper left side of the picture. The cells differ from those found peripheral to the mass, but these cells are slightly atypical. Note the atypical lentiginous component.
	From the left side of the biopsy, peripheral to the expansile mass. There are large, atypical cells in a lentiginous distribution and these are also forming nests at the junction. Keratinocyte hypertrophy is present (can be seen in Spitz' tumors and in melanomas).
	Base of the expansile mass.
	Interior of the expansile mass. Spindle and epithelioid cells are not associated with much stroma.
	One of several mitoses within the expansile mass. A few mitoses were abnormal, as was this one. There is a peculiar regional cytoplasmic variation in the coloration of the large tumor cells that is not often seen in benign melanocytic lesions.
	Small clusters of large cells and a large single cell in a pageoid distribution. There were not many of these. Keratinocyte hypertrophy is also present.