Clinical Features:

• Reactive process of unknown etiology
• Most common on the limbs and trunk of young to middle-aged adults
• Presents as a rapidly growing, painful subcutaneous nodule
• Local recurrence uncommonly occurs.

Histologic Features:

• Well-circumscribed proliferation of interlacing fascicles of plump spindle cells ("tissue culture-like fibroblasts")
• Mitotically active
• Loose myxoid and collagenous background, highly variable in degree of collagenization and myxoid change
• Multiple branching thin-walled blood vessels are interspersed throughout the lesion.
• Focal hemorrhage and lymphocytic inflammation are often seen.
• Foamy histiocytes and osteoclast-like giant cells are sometimes present.
• Immunohistochemically, the spindle cells are positive for MSA and calponin, but negative for desmin, consistent with myofibroblasts.

Cases associated with this book:

Nodular fasciitis
Author: Stephen Lyle, M.D., Ph.D.

Conference: DermatopathologyConsultations.com Teaching Collection