dermatofibroma containing tissue mucin

DERMATOFIBROMA CONTAINING INCREASED TISSUE MUCIN IN CELLULAR AREAS

This is a solitary lesion from an adult.

Increased tissue mucin within the background of a cellular spindle cell skin lesion having storiform figures raises the possibility of dermatofibrosarcoma protuberans (DFSP), particularly a recurrent one. Increased tissue mucin is seen in variants of so many benign and malignant spindle cell tumors that this must not be given primary diagnostic importance in most instances.

In this particular case, there is no infiltration of the subcutis of the type that would be characteristic of a DFSP. The glassy collagen bundles that sometimes form rings in the superficial part of this case are seen in some examples of dermatofibroma and would not be expected in DFSP. The same can be said for the multinucleated histiocytes. There are no vascular or pseudovascular channels of the type found in many giant cell fibroblastomas, and those tumors usually occur in children..

Composite scan power view. The surface of the lesion protrudes above the level of the adjacent skin. Dermatofibromas sometimes do this. There is no infiltration of the subcutis of the type that would be characteristic of a DFSP. There is marked regional variation in the degree of cellularity, and this is sometimes seen in dermatofibromas.

Low power view.

High power view of above. Glassy collagen fibers are seen in this area, and there is a glassy ring (GR) of such material. Sometimes a small blood vessel can be found in the ring (not illustrated here).A few multinucleated histiocytes are present.

Low power view of a cellular area. A few storiform or starburst figures can be seen. The less cellular area in the extreme right side of the image has the features of an ordinary dermatofibroma.

High power view of above. Increased tissue mucin is found between the fibroblasts. This is unusual in this setting, but apparently of no significance.

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	Composite scan power view. The surface of the lesion protrudes above the level of the adjacent skin. Dermatofibromas sometimes do this. There is no infiltration of the subcutis of the type that would be characteristic of a DFSP. There is marked regional variation in the degree of cellularity, and this is sometimes seen in dermatofibromas.
	Low power view.
	High power view of above. Glassy collagen fibers are seen in this area, and there is a glassy ring (GR) of such material. Sometimes a small blood vessel can be found in the ring (not illustrated here).A few multinucleated histiocytes are present.
	Low power view of a cellular area. A few storiform or starburst figures can be seen. The less cellular area in the extreme right side of the image has the features of an ordinary dermatofibroma.
	High power view of above. Increased tissue mucin is found between the fibroblasts. This is unusual in this setting, but apparently of no significance.