Solitary Myofibroma | Dermatopathology

The circumscribed nodular architecture with the biphasic myoid and hemangiopericytomatous pattern is typical in a myofibroma. The pattern of cystic degeneration, hemorrhage and inflammation observed in the hemangiopericytomatous component is also quite common. These lesions are benign with a very low incidence of recurrence even after incomplete excision.

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Slide 1: The excision specimen shows a circumscribed nodular tumor that has a biphasic pattern characterized by discrete foci that are hyalinized to basophilic and somewhat chondroid in quality.

Slide 2: The myxoid appearing cells have somewhat blunt ended appearing nuclei with lightly eosinophilic to basophilic appearing cytoplasm.

Slide 3: The more primitive cellular component is one characterized by cells that range from being rounded to more elongate with a vesicular chromatin and fairly high nuclear to cytoplasmic ratios.

Slide 4: It does exhibit a hemangiopericytomatous morphology in that this undifferentiated spindled and small rounded cell component is intimately associated with blood vessels many of which have a branching staghorn appearance.

Slide 5: The lesion is extensively highlighted by CD34 in terms of the primitive hemangiopericytomatous component.

Slide 6: There is staining for smooth muscle actin throughout the lesion with both components demonstrating strong positivity.

Slide 7: There are a smattering of S-100 positive appearing cells throughout the lesion.