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Superficial Acral (Digital) Fibromyxoma

Definition

  • Superficial spindle cell lesion with myxoid and fibrous stroma, typically located in acral sites

Diagnostic Criteria

  • Vast majority are subungual or periungual, on either fingers or toes
    • Very rare cases located on ankle and leg
  • Superficial lesion with frequent infiltration of dermal collagen and fat
    • Frequently extends into subcutaneous tissue
    • May erode or infiltrate underlying bone
    • Perineural invasion not seen
    • Overlying epidermis may be keratotic, but typically not a cutaneous horn
  • Moderate cellularity with spindled and stellate cells
    • Minimal atypia
    • Occasional large degenerate nuclei and multinucleated cells
    • Mitotic figures rare
    • No necrosis or pleomorphism
    • Mast cells frequent
    • Neutrophils infrequent unless ulcerated
  • Usually a mixture of myxoid stroma and areas of dense hyaline collagen
    • May create an alternating pattern
    • Occasionally one pattern predominates
    • Myxoid areas are Alcian blue positive
    • Infrequently may show cartilaginous or osseous metaplasia
      • One report of fatty metaplasia
  • Capillary proliferation may be prominent in myxoid areas


Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates:: 3/24/12

Supplemental studies

Immunohistology

CD34 70-90% strong pos
CD99 80%
EMA 7-70%
Smooth muscle actin 0-10%
S100, MUC4, keratin negative

Genetic Studies

  • No GNAS1 activating mutations
  • No t(7;16) or t(11;16) or t(17;22)

Differential Diagnosis

 

Superficial Acral Fibromyxoma Acquired Digital Fibrokeratoma
May be keratotic but lacks developed horn Usually has a keratotic horn
Forms a dermal nodule More exophytic lesion
Usually infiltrates surrounding and underlying tissues Circumscribed
Moderate cellularity Hypocellular collagen
Frequently increased vascularity No increased vascularity
Myxoid and collagenous stroma Fibrotic collagenous stroma
EMA may be positive EMA negative

 

Superficial Acral Fibromyxoma Periungual and Subungual Fibroma
Forms a dermal nodule More exophytic lesion, frequently filiform or verrucous
Moderate cellularity No increase in cellularity
Frequently increased vascularity No increased vascularity

 

Superficial Acral Fibromyxoma Superficial Angiomyxoma
Neutrophils uncommon Neutrophils common
Epithelial component rare Frequent epithelial component
Prominent fibrous component mixed/alternating with moderately cellular myxoid areas Predominant hypocellular myxoid component, frequently in pools
EMA variably positive EMA negative

 

Superficial Acral Fibromyxoma Dermal Mucinosis
Moderately cellular Markedly hypocellular
Frequent capillary proliferation Hypovascular
Frequent fibrotic component Purely myxoid

 

Superficial Acral Fibromyxoma Neurofibroma
Alternating myxoid and collagenous areas Random, disorganized pattern
S100 negative S100 positive

 

Superficial Acral Fibromyxoma Sclerosing Perineurioma
Random, fascicular or loose storiform patterns Typically has concentric, onion bulb pattern
CD34 positive CD34 negative
Note: Lesions described as subungual perineuriomas are probably the same lesion as superficial acral fibromyxoma

 

Superficial Acral Fibromyxoma Dermatofibrosarcoma Protuberans
Virtually all acral Usually central, rarely acral
Loose storiform or random pattern Usually has some classic non-myxoid areas with tight storiform
EMA may be positive EMA negative
Apolipoprotein D negative (0/4) Apolipoprotein D positive (90%)
No consistent cytogenetic abnormality t(17;22)

 

Superficial Acral Fibromyxoma Low Grade Fibromyxoid Sarcoma
Virtually all acral Most in deep soft tissues, rarely acral
CD34 usually strong, MUC4 negative CD34 negative to rare faint, MUC4 positive
No mutations involving FUS gene t(7:16) or t(11:16)

 

Superficial Acral Fibromyxoma Cellular Myxoma
Virtually all acral Most in deep soft tissues, rarely acral
No GNAS1 mutations GNAS1 activating mutations

 

Superficial Acral Fibromyxoma Inflammatory Myxohyaline Tumor of Distal Extremities
Virtually all superficial Usually deep
Usually one nodule Usually multinodular
Lacks inflammation Abundant inflammation
Cytologically bland and uniform Reed-Sternberg like cells
May be EMA positive EMA negative

Clinical

  • Mean age mid forties
    • Range 4-86
  • About 20% recur locally, non-aggressively
    • Usually associated with positive margins
  • No metastases

Lists

Soft tissue lesions that frequently are prominently myxoid

Bibliography

  • Hollmann TJ, Bovée JV, Fletcher CD. Digital Fibromyxoma (Superficial Acral Fibromyxoma): A Detailed Characterization of 124 Cases. Am J Surg Pathol. 2012 Feb 24. [Epub ahead of print].
  • Ashby-Richardson H, Rogers GS, Stadecker MJ. Superficial acral fibromyxoma: an overview. Arch Pathol Lab Med. 2011 Aug;135(8):1064-6
  • Prescott RJ, Husain EA, Abdellaoui A, Al-Mahmoud RM, Khan M, Salman WD, Twaij Z, Zelger BG, Zelger B, Al-Daraji WI. Superficial acral fibromyxoma: a clinicopathological study of new 41 cases from the U.K.: should myxoma (NOS) and fibroma (NOS) continue as part of 21st-century reporting? Br J Dermatol. 2008 Dec;159(6):1315-21.
  • Al-Daraji WI, Miettinen M. Superficial acral fibromyxoma: a clinicopathological analysis of 32 tumors including 4 in the heel. J Cutan Pathol. 2008 Nov;35(11):1020-6.
  • Tardío JC, Butrón M, Martín-Fragueiro LM. Superficial acral fibromyxoma: report of 4 cases with CD10 expression and lipomatous component, two previously underrecognized features. Am J Dermatopathol. 2008 Oct;30(5):431-5.
  • Fetsch JF, Laskin WB, Miettinen M. Superficial acral fibromyxoma: a clinicopathologic and immunohistochemical analysis of 37 cases of a distinctive soft tissue tumor with a predilection for the fingers and toes. Hum Pathol. 2001 Jul;32(7):704-14.
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