adult cutaneous myofibroma

CUTANEOUS ADULT MYOFIBROMA

Myofibromatosis was first described in infants and those lesions were often multiple or generalized. Subsequently, solitary lesions having this type of pathology have been described in adults and have been the subject of a moderately large series ^{ref 1}. Many of the solitary myofibromas from adults have a biphasic pattern consisting of fibromyxoid areas containing cells resembling smooth muscle cells plus more cellular areas within which there may be vascular channels resembling those found in pericytomas. The background stroma in the fibromyxoid areas is sometimes hyalinized. The architecture is often lobulated. Other cellular constituents and patterns have led to the conclusion that myofibromas may be related to other tumors having perivascular myoid differentiation ^{ref 2} .

The current case (plus a photomicrograph from another adult case) has the biphasic pattern mentioned above. The myxoid component in the connective tissue was not prominent in the initial sections but is prominent in deeper sections stained another day. The cellular areas were not seen in the deeper sections. Therefore differences in sampling and staining could lead to varying interpretations regarding the pathology of this lesion.

This fragmented specimen was obtained from the dermis and subcutis of the cheek of a 26 year old female. The mass was solitary.

Scan power view of a relatively solid area. The upper half of the mass is less cellular than the lower half. The section was stained lighter than usual.

Medium power view of the upper left part of the mass depicted above. The mass has a scalloped outline in this area. Tissue mucin is present but not prominent in this preparation.

High power view of above. Spindle cells having eosinophilic cytoplasm resemble ordinary smooth muscle cells.

Low power view of one of the deeper sections (stained darker) of the mass. The tumor has more of a fascicular pattern in this area, and there is an interesting structure in the lower right part of the picture. Tissue mucin is prominent in this preparation.

High power view of the interesting structure. This type of structure has been interpreted as 'vascular invasion' but this is not indicative of malignancy in this setting.

High power view from the more cellular area in the tumor depicted in the top (scan) picture.

Medium power view from another example of this type of tumor (another case) showing a cellular area in the lower right part of the picture and a less cellular fibromyxoid nodule in the upper left part. This area has features that can be seen in a pericytoma.

References:

1: Requena L, Kutzner H, Hugel H, Rutten A, Furio V.
Cutaneous adult myofibroma: a vascular neoplasm.
J Cutan Pathol. 1996 Oct;23(5):445-57.

2: Granter SR, Badizadegan K, Fletcher CD.
     Myofibromatosis in adults, glomangiopericytoma, and myopericytoma:
     a spectrum of tumors showing perivascular myoid differentiation.
    Am J Surg Pathol. 1998 May;22(5):513-25.

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	Scan power view of a relatively solid area. The upper half of the mass is less cellular than the lower half. The section was stained lighter than usual.
	Medium power view of the upper left part of the mass depicted above. The mass has a scalloped outline in this area. Tissue mucin is present but not prominent in this preparation.
	High power view of above. Spindle cells having eosinophilic cytoplasm resemble ordinary smooth muscle cells.
	Low power view of one of the deeper sections (stained darker) of the mass. The tumor has more of a fascicular pattern in this area, and there is an interesting structure in the lower right part of the picture. Tissue mucin is prominent in this preparation.
	High power view of the interesting structure. This type of structure has been interpreted as 'vascular invasion' but this is not indicative of malignancy in this setting.
	High power view from the more cellular area in the tumor depicted in the top (scan) picture.
	Medium power view from another example of this type of tumor (another case) showing a cellular area in the lower right part of the picture and a less cellular fibromyxoid nodule in the upper left part. This area has features that can be seen in a pericytoma.