Unusual Diagnosis Of The Week: Digital Mucous Cyst

Earlier this month I received an e-mail asking for information.?? I have changed it slightly:

I have been pouring over the computer, searching for information on a tumor.?? I had removed last week from my left long finger (third finger).?? The pathology report came back as a myxoid tumor.?? I was told it was a tumor, not a cyst.?? Could you help me give me more information?

To begin, most digital myxoid or mucous tumors are cystic in nature.?? Very few are not.?? It is difficult to find much information in the literature, especially the current literature.

Digital mucous cysts (DMCs) are benign ganglion cysts.?? They most often are located at the most distal joint of the finger or in the nail fold.?? Physicians call this joint the distal interphalangeal (DIP) joints.???? The fingers are most commonly involved, but DMCs may occur on the toes. (photo credit)

The etiology of these cysts is not known.?? DMCs are also called myxomatous cutaneous cysts, periungual ganglions, mucous cysts, myxoid cysts, synovial cysts, dorsal cysts, nail cysts, cystic nodules, digital mucoid cysts, digital myxoid cysts, and digital mucinous pseudocysts.

The cyst often has a smooth shiny surface on exam.?? If located near the nail, there will often be a groove in the nail as in the photo above.?? The cyst’s size may vary.

If the cyst is asymptomatic, then treatment is not required.?? Recurrence is common regardless of which treatment is used.

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  Aspiration of the contents (72% success rate with multiple aspirations, 2-5 treatments)
  


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  Cyrotherapy (56% to 86% success rate)
  


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  Steroid injection
  


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  Surgical excision (88% to 100%)
  

Restriction of joint mobility, nail dystrophy, and changes to the contour of the proximal nail fold are potential drawbacks.

When considering a difference diagnosis keep in mind the following:

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  Epidermoid cyst
  


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  Heberden node or Rheumatic nodule
  


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  Fibrokeratoma (DMCs may resemble this when they form between the proximal nail fold and the nail and protrude with a keratoticlike tip.)
  


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  Giant-cell tendon sheath tumor
  


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  Myxoid malignant fibrous histiocytoma
  


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  Myxoid variant of liposarcoma (These are less likely to present as firm circumscribed masses and more likely to be deeply seated.)
  

REFERENCES

Digital Mucous or Myxoid Cyst

Digital mucous cyst a?? emedicine dermatology, the online textbook

health.com/adult/myxoidCyst-treatments.htm" >Myxoid Cyst

Cystic Lesions of the Hands; Clinical Advisor, November 12, 2008; Noah S. Scheinfeld, MD, JD

Digital myxoid cysts: a review; Cutis; Feb 1986;37(2):89-94; Sonnex TS.

Myxoid Cysts; JAMA, Dec 1965; 194: 1239; Frederick A. J. Kingery

Ganglion of the Distal Interphalangeal Joint (Myxoid Cyst): Therapy by Identification and Repair of the Leak of Joint Fluid; ARCH DERMATOL/VOL 137, MAY 2001; David de Berker, MRCP; Clifford Lawrence, FRCP

Ray Amputation As A Treatment for Recurrent Myxohyaline Tumor of the Distal Extremity; Plastic and Reconstructive Surgery. 111(4):1573-1574, April 1, 2003; Mowlavi, Arian; Quinn, Brendon M.; Zook, Elvin G.; Milner, Stephen

Soft-Tissue Sarcomas of the Upper Extremity: Surgical Treatment and Outcome; Plastic and Reconstructive Surgery. 113(1):231-232, January 2004; Steinau, Hans-Ulrich; Kuhnen, Cornelius

Soft-Tissue Chondroma in the Thumb; Plastic and Reconstructive Surgery. 110(6):1599-1600, November 2002; Avc, G??lden; Aydogdu, Eser; Ydrm, Serkan; Ak??z, Tayfun