This presentation details the pathological analysis of a large (15 cm) soft tissue mass excised from the vulvar/perivaginal region of a 35-year-old woman. The diagnosis established is Deep Angiomyxoma, formerly known as Aggressive Angiomyxoma.
The lesion is characterized by hypocellularity, bland spindle cells, and a pale, edematous, and finely collagenous background matrix (often appearing pink rather than classically mixoid/blue). Key diagnostic features include highly variable vascularity—ranging from small capillaries to large, thick-walled muscular vessels—and the presence of thin wisps or fascicles of smooth muscle often spinning off from the vessels.
The presenter emphasizes that the "aggressive" designation refers to the tumor's size and deeply infiltrative nature, which leads to high recurrence risk due to difficulty in achieving complete surgical resection, not malignant biological behavior. The presentation concludes by contrasting the features of Deep Angiomyxoma with its more superficial counterpart, Cutaneous Myxoma (Superficial Angiomyxoma).
Deep Angiomyxoma (Formerly Aggressive Angiomyxoma) Pathology Review
0:00 Case Introduction: The case involves a 35-year-old woman with a large (15 cm) soft tissue mass spanning the vulva, underlying perivaginal, and pelvic soft tissue.
1:13 Naming Convention: The diagnosis is Deep Angiomyxoma (previously Aggressive Angiomyxoma). The term "aggressive" is misleading; it denotes the large, infiltrative nature and high recurrence potential due to difficulty obtaining clear surgical margins, not malignant growth or rapid proliferation.
2:20 Matrix Characteristics (The "Mixoma" Part): The background matrix often appears pale pink and edematous, containing fine wisps of collagen (0:03:16), rather than the deep blue traditionally associated with myxoid tumors.
3:35 Vascular Characteristics (The "Angio" Part): A key feature is the wide range of vessel sizes and shapes, from small, delicate capillaries/venules (0:04:00) to large, thick-walled muscular vessels, often exhibiting intimal hyperplasia (0:03:47).
4:17 Cellular Characteristics: The lesion is typically hypocellular. Cells are sparse, bland, and appear spindle-to-stellate (0:04:30), lacking significant atypia or mitosis.
4:57 Diagnostic Pearl – Smooth Muscle Wisps: A helpful visual clue is the presence of thin fascicles of pink spindle cells (interpreted as smooth muscle bundles) that often arise from the edges of vessels and swirl out into the loose background (0:05:55).
Immunohistochemistry frequently shows positivity for Desmin, Estrogen Receptor (ER), and Progesterone Receptor (PR).
A subset of cases exhibits rearrangements of the HMGA2 gene (0:08:01).
8:59 Differential Diagnosis Key Takeaway: Deep Angiomyxoma is distinguished from Superficial Angiomyxoma (Cutaneous Myxoma) mainly by size and location. Deep Angiomyxomas are large (often >5 cm) and infiltrate deep pelvic soft tissues, whereas superficial variants are small and confined to the dermis/subcutis.
9:26 Contrast with Superficial Angiomyxoma (Cutaneous Myxoma): Superficial lesions are small, circumscribed, and often have a more abundant, typically blue mixoid background. Their vessels are typically thin and delicate, sometimes resembling chicken wire (0:09:43), contrasting with the highly variable vessels of the deep variant.