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cutaneous myxoma

Wednesday 21 June 2017

superficial angiomyxoma


Definition: A cutaneous myxoma, a.k.a. superficial angiomyxoma, consists of a multilobulated myxoid mass containing stellate or spindled fibroblasts with pools of mucin forming cleft-like spaces. There is often a proliferation of blood vessels and an inflammatory infiltrate.


- hypocellular tumors / hypocellularity
- composed of bland cells,
- no mitotic activity,
- no lipoblasts,
- scant blood vessels;
- may have focal histiocytes
- Slightly more cellular with collagenized capsule at periphery
- May have areas of increased vascularity or be hypercellular (Am J Surg Pathol 1998;22:1222)
- Slightly basophilic matrix with usually a few spindle cells at high power with oval nuclei
- May have central mucinous cyst
- At periphery, may infiltrate striated muscle and be associated with muscle atrophy


Immunostaining is :
- positive for vimentin ,
- negative for cytokeratin and desmin ,
- variable for CD34 (50%), Factor VIIIa , SMA , MSA and S-100.

Clinically, it may present as solitary or multiple flesh-colored nodules on the face, trunk, or extremities. Local recurrence is common.

It may occur as part of the Carney complex , and is sometimes the first sign.

Differential diagnosis : cutaneous myxoid tumors

Myxoid or mucinous background change is a common finding in a wide variety of cutaneous tumors and other diseases.

Myxoid tumors often have overlapping features and may show significant heterogeneity from area to area within a given specimen and from individual case to case.

As prognosis and treatment vary considerably between many of these entities, accurate diagnosis is essential.

Myxoid tumors include :
- superficial angiomyxoma (cutaneous myxoma )
- superficial acral fibromyxoma (digital fibromyxoma )
- dermal nerve sheath myxoma (conventional neurothekeoma )
- myxoid dermatofibrosarcoma protuberans ,
- giant cell fibroblastoma ,
- low-grade fibromyxoid sarcoma ,
- myxofibrosarcoma ,
- myxoinflammatory fibroblastic sarcoma

Molecular biology

- GNAS1 mutations in 61% of intramuscular myxomas (Mod Pathol 2009;22:718)
- No cytogenetic aberrations

See also

- angiomyxoid tumors
- cutaneous tumors
- myxomas