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superficial acral fibromyxoma

Tuesday 23 November 2004

digital fibromyxoma

Definition: Superficial acral fibromyxoma (SAF) is a newly characterised soft tissue tumour of the hands and feet with a tendency to involve the nail region.

Images

- superficial acral fibromyxoma

Digital fibromyxoma (first described by Fetsch and colleagues as "superficial acral fibromyxoma") is a distinctive soft tissue tumor with a predilection for the subungual or periungual region of the hands and feet.

Clinical features

- Adults (range 14 to 72 years, median 46 years).
- M:F=2:1.
- Site: great toe, other toes; fingers;palm; nail region.
- The lesions are generally slow-growing and painless.

Macroscopy

- The tumours range from 0.6 to 5.0 cm (median 1.5 cm).
- They are soft to firm with a gelatinous or solid off-white cut surface.

Micrsocopy

- The lesions are dermal or subcutaneous.
- A few involve fascia or periosteum.
- Cellularity is moderate, consisting of stellate or spindled fibroblast-like cells in a myxoid, myxocollagenous or collagenous matrix.
- A storiform pattern is seen.
- Multinucleate cells are present.
- Some tumors show moderate or pronounced nuclear pleomorphism.
- Some tumors show mitoses, up to 7 per 50 HPF.
- Most cases contain mast cells and some a mild lymphocytic infiltrate.
- The margins are pushing or infiltrative.

IHC

- CD34+
- S100-

Differential diagnosis

See: Differential diagnosis of cutaneous myxoid lesions or subcutaneous myxoid lesions.

- fibrous histiocytoma variant:

  • abundant myxoid matrix rare,
  • more storiform,
  • more stellate interface with normal stroma,
  • CD34 negative.

- dermatofibrosarcoma protuberans:

  • rare on extremities,
  • may contain abundant myxoid stroma,
  • CD34 positive, but usually retain foci of tight storiform architecture,
  • have a more infiltrative growth pattern
  • lack EMA immunoreactivity.

- cutaneous myxoma (superficial angiomyxoma):

  • weakly linked to Carney complex,
  • abundant stromal mucin forming pools with peripheral acellular cleftlike spaces.
  • May be CD34 positive.

- sclerosing perineurioma:

  • strong predilection for fingers and palms of young adults,
  • abundant dense collagen,
  • cords and onion-bulb pattern of small epithelioid and spindled cells,
  • EMA positive but CD34 negative.

- acquired fibrokeratoma (digital fibrokeratoma) :

  • classical (type 1); smaller, more superficial, more exophytic, less cellular, less vascular, collagen in parallel bundles
  • variant (type 2); more closely resemble acral fibromyxoma, being more cellular with less well organised collagen and a storiform pattern, but are more superficial and have minimal myxoid matrix.

- periungual fibroma/subungual fibroma of tuberous sclerosis (Koenen tumour)

  • multifocal
  • polypoidal/verrucous
  • fibrous connective tissue
  • less cellular.

- acral myxoinflammatory fibroblastic sarcoma (inflammatory myxohyaline tumour of the distal extremities with virocyte or Reed-Sternberg-like cells):

  • peak incidence in midadult life,
  • predilection for extremities,
  • subcutis and deep soft tissues,
  • multinodular with poorly defined margins,
  • stellate and spindled cells with large pleomorphic nuclei and inclusion-like nucleoli,
  • substantial mixed inflammatory component,
  • EMA negative,
  • may be CD34 positive.

Molecular biology

Sequencing of 8 digital fibromyxomas failed to reveal mutations in exon 8 or 9 of GNAS1, in contrast to intramuscular or cellular myxoma. (22367301)

Management

- Complete excision, in view of uncertain behavior, especially in the cases with pleomorphism or mitoses.

Prognosis

- May recur locally. No metastases reported.

See also

- myxoid tumors

- acral tumors

References

- Digital Fibromyxoma (Superficial Acral Fibromyxoma): A Detailed Characterization of 124 Cases. Hollmann TJ, BovĂ©e JV, Fletcher CD. Am J Surg Pathol. 2012 Feb 24. PMID: 22367301

- Meyerle JH, Keller RA, Krivda SJ. Superficial acral fibromyxoma of the index finger. J Am Acad Dermatol. 2004 Jan;50(1):134-6. PMID: 14699384

- Kazakov DV, Mentzel T, Burg G, Kempf W. Superficial acral fibromyxoma: report of two cases. Dermatology. 2002;205(3):285-8. PMID: 12399679

- 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. PMID: 11486169