Think outside the breast

22 year old woman with recent onset of painful breast mass

Image 1.  Core needle biopsy specimen contains a spindled cell proliferation; note small amount of normal breast tissue at upper left.

Image 2.  Spindled cells are arranged in swirling fascicles and are associated with a myxoid background and focal hemorrhage.

Image 3. Spindled cells have the appearance of cells in tissue culture.  Note areas of hemorrhage.

Image 4.  Occasional mitotic figures are present (center of field).

Diagnosis:  Nodular fasciitis

Discussion:  This is a classic presentation of nodular fasciitis;  rarely do patients remember associated trauma.  Usually nodular fasciitis affects the trunk or forearm; involvement of the breast is uncommon. The bland spindled cells are arranged in swirling fascicles, and the associated edematous/myxoid stroma gives the appearance of cells in tissue culture.  Nodular fasciitis should resolve over a few months, and excision is not necessary.