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Skin nonmelanocytic tumor

Fibrous, fibrohistiocytic and myofibroblastic neoplasms

Superficial angiomyxoma


Charmaine Ilagan, M.D.
Juan Putra, M.D.

Last author update: 6 May 2025
Last staff update: 6 May 2025

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PubMed search: Superficial angiomyxoma

Charmaine Ilagan, M.D.
Juan Putra, M.D.
Page views in 2024: 56
Page views in 2025 to date: 15,429
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Virtual slides | Cytology description | Cytology images | Positive stains | Negative stains | Molecular / cytogenetics description | Videos | Sample pathology report | Differential diagnosis | Additional references | Practice question #1 | Practice answer #1 | Practice question #2 | Practice answer #2
Cite this page: Ilagan C, Putra J. Superficial angiomyxoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticsuperficialangio.html. Accessed September 15th, 2025.
Definition / general
  • Superficial angiomyxoma (cutaneous myxoma) is a rare, benign lobulated / multinodular lesion composed of bland spindled and stellate cells in myxoid stroma with arborizing, thin walled vessels
  • Initially described by Carney et al. in 1985 in association with Carney complex (Medicine (Baltimore) 1985;64:270)
Essential features
  • Rare, benign cutaneous neoplasm with a propensity for local recurrence, ~30 - 40% after incomplete excision
  • Presents as a slow growing, painless mass
  • Well circumscribed mass (~1 - 5 cm) with yellow gelatinous cut surface
  • Multiple lesions may occur in the setting of Carney complex
Terminology
  • Cutaneous myxoma
ICD coding
  • ICD-O: 8841/0 - superficial angiomyxoma
  • ICD-10: D21.9 - benign neoplasm of connective and other soft tissue, unspecified
  • ICD-11: 2E84.0 & XH58A9 - benign fibrogenic or myofibrogenic tumor of skin & superficial angiomyxoma
Epidemiology
Sites
Pathophysiology
  • Unknown
Etiology
  • Unknown
  • Multiple lesions may arise in the setting of Carney complex
    • Carney complex is due to either mutations in PRKAR1A gene that encodes protein kinase A regulatory subunit 1 alpha or MYH8 gene that encodes perinatal myosin (Lancet Oncol 2005;6:501)
Clinical features
  • Presents as soft, slow growing, painless papule or polypoid cutaneous mass
  • Multiple lesions may arise in the setting of Carney complex (J Dermatol 2002;29:790)
    • Carney complex inherited in an autosomal dominant manner is characterized by skin pigment abnormalities, cutaneous, cardiac and breast myxomas, endocrine tumors or overactivity and psammomatous melanotic schwannomas (GeneReviews: Carney Complex [Accessed 19 December 2024])
Diagnosis
  • Definitive diagnosis is based on the excision specimen
Radiology description
Radiology images

Images hosted on other servers:
Ultrasound

Ultrasound

CT

CT

MRI   MRI

MRI

Prognostic factors
Case reports
Treatment
Clinical images

Images hosted on other servers:
Left shoulder mass

Left shoulder mass

Protruding pinna mass

Protruding pinna mass

Left axillary mass

Left axillary mass

Gross description
  • Usually 1 - 5 cm (Am J Surg Pathol 1988;12:519)
  • Usually a well circumscribed solitary lesion with yellow gelatinous cut surface
  • Vaguely multinodular due to presence of thin fibrous septa
  • May be poorly circumscribed
Gross images

Images hosted on other servers:
Well defined, yellow mass

Well defined, yellow mass

Well defined, encapsulated mass

Well defined, encapsulated mass

Well encapsulated, yellow mass

Well encapsulated, yellow mass

Microscopic (histologic) description
  • Well circumscribed lobulated / multinodular lesion located in dermis; it can extend into underlying subcutis
  • Vague lobules divided by thin fibrous septa
  • Hypocellular lesion composed of haphazardly arranged, bland spindled and stellate cells embedded in myxoid stroma, sometimes forming irregular clefts
  • Spindled and stellate cells with bland nuclei often with intranuclear vacuoles and inconspicuous nucleoli
  • Binucleated or multinucleated cells may be seen
  • Arborizing, thin walled vessels, often prominent
  • Scattered mixed inflammatory infiltrates in stroma, predominantly neutrophils
  • Mast cells often present
  • No significant atypia, necrosis or increased mitotic figures
  • Entrapped benign epithelial elements (epidermoid cyst or strands of squamous or basaloid cells) likely represent entrapped adnexa in up to 25% of cases (Ann Diagn Pathol 2000;4:99)
Microscopic (histologic) images

Contributed by Charmaine Ilagan, M.D. and Juan Putra, M.D.
Well defined tumor with myxoid stroma involving the dermis

Well defined tumor

Spindled and stellate cells   Spindled and stellate cells

Spindled and stellate cells

Thin walled vessels

Thin walled vessels


Intranuclear vacuoles   Intranuclear vacuoles

Intranuclear vacuoles

CD34

CD34

PRKAR1A

PRKAR1A

Virtual slides

Images hosted on other servers:
Soft palate mass

Soft palate mass

Right breast mass

Right breast mass

Cytology description
Cytology images

Images hosted on other servers:

Spindle cells, myxoid background

Negative stains
Molecular / cytogenetics description
Videos

Superficial angiomyxoma (cutaneous myxoma) and other cutaneous myxoid lesions by Dr. Jerad Gardner

Superficial angiomyxoma (cutaneous myxoma) by Dr. Jerad Gardner

Sample pathology report
  • Soft tissue, left axilla, excision:
    • Superficial angiomyxoma (see comment)
    • Comment: Sections demonstrate a well circumscribed lobulated lesion involving the dermis and extending to subcutis. The hypocellular lesion is composed of bland spindled and stellate cells with eosinophilic cytoplasm embedded in myxoid stroma. There is no significant atypia or increased mitotic activity identified. Scattered arborizing thin walled vessels and neutrophils in the stroma are identified. Immunohistochemical stains show that the lesional cells are positive for CD34 and SMA, while negative for cytokeratin AE1 / AE3, S100, GFAP, desmin, MUC4, ER and PR.
Differential diagnosis
  • Cutaneous focal mucinosis (Cureus 2021;13:e18618):
    • Usually smaller lesions (< 1 cm)
    • Mucin deposition usually in upper dermis
    • Rarely extends into subcutis
    • Lacks prominent vasculature and scattered stromal neutrophils
  • Intramuscular myxoma:
    • Often located deep within the muscles of extremities
    • Infiltrating into adjacent skeletal muscle
    • Lacks prominent vasculature
    • GNAS mutation
    • May be associated with Mazabraud syndrome
  • Myxoid neurofibroma:
    • Spindle cells with wavy nuclei in myxoid stroma
    • Vasculature is less conspicuous
    • Positive for SOX10, S100, CD34
    • Negative for SMA, desmin
  • Dermal nerve sheath myxoma (Diagnostic Histopathology 2016;22:152):
    • Commonly occurs in extremities, most often in fingers
    • Rarely involves head and neck
    • Well circumscribed myxoid lobules separated by thick fibrous septa
    • Lesional cells can be spindled or epithelioid
    • Cellular interconnections are common
    • Positive for SOX10, S100, GFAP
    • Negative for SMA, desmin
  • Superficial acral fibromyxoma (Diagnostic Histopathology 2016;22:152):
    • Periungual or subungual region of fingers and toes
    • Moderately cellular lesion composed of spindled to stellate cells arranged in loose storiform or fascicular pattern in myxoid and collagenous stroma
    • Prominent microvasculature
    • Positive for CD34 (diffuse), CD99 (diffuse), SMA (focal)
    • Loss of nuclear Rb expression
  • Aggressive angiomyxoma:
    • Larger lesions (> 10 cm) in deep soft tissue of genital, pelvic and perineal regions, usually in females
    • Infiltrative lesion with bland spindled and stellate cells
    • Variably sized vessels with small thin walled to large thick walled vessels, often with hyalinization
    • Myoid bundles near vessels
    • HMGA2, ER, PR positive
  • Myxoid liposarcoma:
    • Usually in deep soft tissue of extremities, most common in the thigh
    • Characteristic plexiform vasculature with scattered lipoblasts
    • Subset may show high grade hypercellular areas
    • t(12;16) FUS::DDIT3 or very rarely t(12;22) EWSR1::DDIT3
  • Low grade fibromyxoid sarcoma (Diagnostic Histopathology 2016;22:152):
    • Involves proximal extremities and trunk
    • Bland spindle cells in whorling or fascicular pattern
    • Alternating collagenous and myxoid stroma
    • Arcading vessels with perivascular sclerosis
    • MUC4 and EMA positive
    • t(7:16) FUS::CREB3L2 fusion or t(11;16) FUS::CREB3L1 fusion
  • Low grade myxofibrosarcoma (Diagnostic Histopathology 2016;22:152):
    • Multinodular growth pattern with infiltrative margins in myxoid stroma
    • Hyperchromatic pleomorphic cells with curvilinear vessels
    • Necrosis and increased mitotic figures (including atypical mitotic figures) seen in intermediate and high grade tumors
Practice question #1


A 25 year old man presents with a painless mass on the posterior neck that gradually developed over 2 months. The mass, which measures 2 cm, is well circumscribed and has a gelatinous cut surface. The tumor cells are positive for CD34, while negative for MUC4, ER, PR and SOX10. What is the diagnosis?

  1. Aggressive angiomyxoma
  2. Low grade fibromyxoid sarcoma
  3. Myxoid neurofibroma
  4. Superficial angiomyxoma
Practice answer #1
D. Superficial angiomyxoma. The image above shows superficial angiomyxoma, which is a slow growing, painless mass that usually measures 1 - 5 cm in its greatest dimension. Grossly, the tumor is well circumscribed and has a yellow, gelatinous cut surface. Microscopically, the tumor cells are bland spindled and stellate cells in myxoid stroma with prominent arborizing thin walled vessels. The tumor cells are positive for CD34, while negative for ER, PR, SOX10 and MUC4. Answer A is incorrect because aggressive angiomyxomas are usually larger (> 10 cm) and involve the deep soft tissue of the genital, pelvic and perineal regions. They are infiltrative lesions with bland spindled and stellate cells and have variably sized vessels, often with hyalinization. The tumor cells are positive for ER, PR and HMGA2. Answer B is incorrect because low grade fibromyxoid sarcomas have bland spindle cells in whorling or fascicular pattern in alternating collagenous and myxoid stroma. The tumor cells are positive for MUC4 and EMA. t(7:16) FUS::CREB3L2 or t(11;16) FUS::CREB3L1 are characteristic gene fusions for low grade fibromyxoid sarcoma. Answer C is incorrect because myxoid neurofibromas have spindle cells with wavy nuclei in myxoid stroma and less conspicuous vasculature. The tumor cells are positive for SOX10, S100 and CD34.

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Reference: Superficial angiomyxoma
Practice question #2
Which of the following is true regarding superficial angiomyxoma?

  1. It has no metastatic potential
  2. Multiple lesions may be associated with Mazabraud syndrome
  3. t(12;16) FUS::DDIT3 gene fusion is characteristic
  4. Tumor cells exhibit marked pleomorphism with presence of necrosis and increased mitosis
Practice answer #2
A. It has no metastatic potential. Answer B is incorrect because multiple superficial angiomyxomas may be associated with Carney complex. Mazabraud syndrome is associated with intramuscular myxoma and fibrous dysplasia. Answer C is incorrect because t(12;16) FUS::DDIT3 gene fusion is seen in myxoid liposarcoma. Answer D is incorrect because tumor cells in superficial angiomyxoma are bland spindled and stellate cells with no significant atypia, necrosis or increased mitosis.

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Reference: Superficial angiomyxoma
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