Path Quiz Case-1   Diagnosis:

  Case1: Case history and histopathology images:

Gross Image:click

On gross examination the tumours are lobulated, soft to rubbery, solid masses, usually  more than10 cms in diameter. The cut surface reveals a glistening, soft homogeneous appearance. Recurrent tumours show more prominent areas of hemorrhage and fibrosis.

Histopathology Image1:click ; Histopathology Image2:click

Histologically, the tumours are infiltrative, poorly circumscribed and are composed of bland round ,spindle or stellate cells together with  non-arborizing blood vessels of varied caliber, embedded in a hypocellular myxoid stroma. The vessels are often thickened or hyalinized. Thin bundles of smooth muscle fibres may be present in the stroma and around the vessels. Numerous foci of  fresh hemorrhage are present around the blood vessels. There is no evidence of atypia and any mitotic activity.
The backround stroma stains positively with alcian blue.

Image Link(Mexico): click

Immunohistochemical staining reveals that the tumour cells are immunoreactive for desmin, muscle specific actin and vimentin. Estrogen and progesteron receptor protein may be positive. The tumour cells are immunonegative for S100 protein, Factor VIII related antigen, carcinoembryonic antigen and cytokeratin.

The neoplastic cells of aggressive angiomyxoma exhibit fibroblastic and myofibroblastic features and appear to be hormonally influenced.

Cytogenetic analysis reveals chromosomal translocation involving chromosome 12 associated with rearrangement of the HMGIC gene. HMGIC expression in aggressive angiomyxoma is of value in the distinction of  difficult cases from its histological  mimics.

Differential Diagnosis:

Visit: Myxoid Tumours of Soft Tissue

Angiomyofibroblastoma:click  This tumour is probably related to aggressive angiomyxoma and is derived from myofibroblasts and perivascular stem cells. Unlike aggressive angiomyxoma this tumour exhibits the following features: Tumour size less than 8cm , well circumscribed border, non infiltrative tumour, higher cellularity, prominent vascularity, plump stromal cells, minimal stromal mucin and rarely extravasation of red blood cells.
  
Cellular angiofibroma:click  Benign lesion with no evidence of recurrence. Small lesion , less than 3cm in diameter. The tumour is composed of spindle cells, bundles of collagen, hyalinized blood vessels and mature adipocyts, set in a loose cellular stroma. Mitotic figures are conspicuous in some cases. Immunohistochemistry reveals immunopositivity for vimentin and CD34 and immunonegativity for actin, desmin and S100 protein.

Superficial angiomyxoma: Poorly circumscribed tumour with nodular growth pattern and composed of spindle cells set in a hypocellular stroma. Occasional binucleated and multinucleated cells are present. A mixed inflammatory infiltrate together with neutrophils are present in all cases. Cystic structures, strands of squamous epithelium or buds of basaloid cells are also identified.

Leiomyoma of vulva: The two variants commonly noted in vulva are myxoid and epithelioid . In problematic cases immunostains play an important role in establishing the diagnosis.

Cervicovaginal myofibroblastoma: Moderate to highly cellular tumour composed of spindle and stellate cells. In areas, the tumour cells show  lacelike or sievelike growth pattern, and vague fascicular pattern in more cellular areas. Abstract

The differential diagnosis also includes fibroepithelial polyps, intramuscular  myxoma, spindle cell lipoma,  myxoid neurofibroma,  fibromatosis, myxoid liposarcoma, myxoid leiomyosarcoma, embryonal rhabdomyosarcoma and myxoid variant of malignant fibrous histiocytoma.