Cellular angiofibroma (vulva) - histology

Case contributed by Dr Mikkaela McCormack

Presentation

Patient seen in the Outpatient Department for a 'cyst' on her vulva. The lesion was removed some weeks later as a day procedure case and the specimen was sent to pathology.

Patient Data

Age: 50 years
Gender: Female

A solid circumscribed, rounded lesion composed of spindle cells set within a fibrous stroma.  The spindle cells display mildly irregular nuclei with inconspicuous nucleoli and a scant amount of cytoplasm.  Mitotic activity is minimal and necrosis is not identified.  There is no significant perivascular hyalinisation and a patchy mild perivascular lymphocytic infiltrate is present.  Scattered mast cells are also seen. 

20x H&E: well-circumscribed, solid lesion.

40x H&E: haphazard intersecting moderately cellular fascicles of spindle cells with scattered blood vessels.

200x H&E: perivascular chronic inflammatory cells.

200x H&E: cytologically bland nuclei with inconspicuous mitotic activity.

40x CD31: highlights vessels within lesion.

40x C-kit: highlights scattered mast cells.

100x ER: diffusely positive.

Case Discussion

Cellular angiofibroma is a benign soft tissue lesion found in the inguinal, vulval or scrotal regions, usually in middle aged+ adults. The cells are myofibroblastic in nature. They are well-circumscribed and comprise spindle cells with morphology described above, and show variable mitotic activity (not atypical, and most often minimal in number). Scattered mast cells are often also present and there is a fine fibrocollagenous stroma with no necrosis. They usually show small prominent vessels with hyalinised walls, which this case doesn't show well, however, the morphology and immunohistochemical findings fit with this diagnosis rather than one of the other  differential diagnoses possible in this location:

  • Angiomyofibroblastoma: Usually also well-circumscribed, variable cellularity - paucicellular background with clustering of rounded cells around smaller, thin-walled vessels, desmin +
  • Aggressive angiomyxoma: Infiltrative, aggressively growing lesion, much less cellular with a more myxoid/loose appearing background, desmin +
  • Leiomyoma: Fascicular growth pattern, with cells containing more cytoplasm and nuclear features more consistent with smooth muscle cells (plumper, blunt-ended cigarette nuclei), desmin+
  • Solitary fibrous tumor: Same spindly cells, but hypo- and hyper-cellular areas, hyalinised stroma between cells, CD34 +

These lesions are usually benign and do not recur, however, case reports of malignant forms have been published.

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