Peer Reviewed

Photoclinic

Digital Mucous Cyst

Volume 59 - Issue 3 - March 2019

Authors:
Zachary A. Curry, BS
Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, North Carolina

Kathryn L. Anderson, MD
Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, North Carolina

Steven R. Feldman, MD, PhD
Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine; Department of Pathology, Wake Forest School of Medicine; and Department of Social Sciences & Health Policy, Wake Forest School of Medicine, Winston-Salem, North Carolina

Citation:
Curry ZA, Anderson KL, Feldman SR. Digital mucous cyst. Consultant. 2019;59(3):93-94.

 

A 76-year-old white woman presented to the dermatology clinic with a papule on the dorsum of the left third digit, near the proximal nail fold, causing nail dystrophy with a longitudinal groove (Figure).

Digital mucous cyst
Figure. A 76-year-old white woman presented with a papule (black arrow) on the dorsum of the left third digit, near the proximal nail fold, causing nail dystrophy with a longitudinal groove (white arrow).

The patient’s medical history was significant for osteoarthritis, and she had a dermatologic history of actinic keratosis, basal cell carcinoma, and seborrheic keratosis. The papule had been present for several months. It was asymptomatic, without ulceration, discharge, pain, or functional limitations. The patient was concerned about potential malignancy and nail dystrophy.

No imaging or diagnostic tests were conducted. A clinical diagnosis of digital mucous cyst (DMC) was made. After discussing the diagnosis and treatment options, the patient opted for observation.

DISCUSSION

DMCs, also called myxoid cysts or myxoid pseudocysts, are papules or nodules occurring between the distal interphalangeal joint (DIP) and the proximal nail fold. DMCs range in size, with an average diameter of approximately 5 mm. They are most commonly located in the medial or lateral nail fold or under the nail plate.1

DMCs typically are painless but can cause epidermal ulceration or nail dystrophy. Coloration varies from skin-colored to reddish purple with polymorphic telangiectasias that blanch with pressure.2,3 Drainage of translucent mucinous material following excoriation is common.4 The most common nail changes caused by DMCs in the nail fold are longitudinal grooves (as in our patient’s case), concave canaliform dystrophy, and transverse lines.5

There are 2 histopathologic varieties of DMCs: dermal fibroblast-derived DMCs that contain mucin but lack a capsule (pseudocysts), and synovial-derived DMCs with a pseudocapsule (ganglion type).6 The latter type often contains a pedicle connecting to the synovial capsule of the DIP.1,7

The etiology of DMCs is unknown but may involve local inflammation of the tissue or joint. DMCs of both types typically present after 40 years of age and are associated with osteoarthritis and osteophyte formation in the DIP, suggesting that joint degeneration may contribute to cyst formation.1,5 However, osteophytes are not required for development, and the location of the DMC relative to the DIP does not reliably indicate histopathologic type.8 Multiple DMCs in a single patient could indicate trauma to the DIPs such as repetitive compression from an occupational task.9

The diagnosis of DMCs is clinical and is based on characteristic location, size, and coloration. Transillumination can be used to visualize the cystic space10 and rule out solid lesions. Magnetic resonance imaging (MRI) or ultrasonography are not indicated but can be useful in subungual presentations.1,11

Treatment options vary widely and can be chosen based on patient preferences and office equipment. Observation is recommended for asymptomatic lesions. Surgical excision is common, with a 16.7% to 22.5% recurrence rate after 1 year.8,12 Needling and expression can be performed in-office with sterile needing, with a success rate of approximately 70%,13 but requires repeated follow-up drainage and poses significant infection risk. This includes a risk of septic arthritis with communication to the DIP. DMCs of the ganglionic type can be treated with intra-articular dexamethasone and lidocaine, with a success rate of 52.2%.14 Other treatment options such as infrared coagulation15 and laser ablation16,17 require specialized equipment. Polidocanol injection has been successful, with resolution in 77.8% of patients at 12 weeks postprocedure.18 Long-term recurrence following polidocanol injection may be as low as 8.3% as assessed in a smaller cohort of patients.19

DIFFERENTIAL DIAGNOSIS

Because the differential diagnosis of digital tumors is broad,20 it is important to exclude malignant tumors, which was our patient’s concern. Transillumination increases the likelihood of a DMC versus a solid tumor. Ultrasonography, MRI, or biopsy can aid if the diagnosis is uncertain, particularly in cases with a subungual presentation.

Malignant lesions can present in the digit. Nodular basal cell carcinoma can present as pink papules with telangiectasias21 mimicking a DMC. Squamous cell carcinoma can present with erythema or scaling papules or plaques.22 Periungual squamous cell carcinoma is associated with human papillomavirus infection and often presents as treatment-resistant verrucae.23 Melanoma typically presents as a macule with irregular borders and multiple colors.24 However, biopsy may be needed to exclude amelanotic melanoma, which can present as an erythematous macule or plaque.24 Benign lesions of the digits with periungual presentation include verrucae and pyrogenic granulomas. Verrucae are often found on the hands with heterogenous coloration (mosaic pattern) and vascular structures including dotted and looped vessels visible with dermoscopy,25 which can mimic DMCs. However, hyperkeratosis is more likely with verrucae.25 Pyogenic granulomas can be associated with mechanical trauma of the digit but often present as exophytic ulcerated masses that are highly vascular,26 in contrast to a DMC.

Proper diagnosis of DMCs based on clinical presentation can avoid unnecessary testing and properly exclude both malignant and benign digital lesions. While there are a variety of options for treating DMCs, patients may elect conservative management of asymptomatic lesions following education and reassurance.

REFERENCES:

  1. Drapé JL, Idy-Peretti I, Goettmann S, et al. MR imaging of digital mucoid cysts. Radiology. 1996;200(2):531-536.
  2. Chae JB, Ohn J, Mun J-H. Dermoscopic features of digital mucous cysts: a study of 23 cases. J Dermatol. 2017;44(11):1309-131
  3. Salerni G, Alonso C. Digital mucous cyst. N Engl J Med. 2012;366(14):1335.
  4. Fernandez-Flores A. Transepidermal elimination of mucin is a very common but not yet reported phenomenon in digital myxoid cysts: a study of 35 cases. J Cutan Pathol. 2015;42(12):947-977.
  5. Lin Y-C, Wu Y-H, Scher RK. Nail changes and association of osteoarthritis in digital myxoid cyst. Dermatol Surg. 2008;34(3):364-369.
  6. Rongioletti F, Barnhill RL. Deposition disorders. In: Barnhill RL, Crowson AN, Magro CM, Piepkorn MW, eds. Dermatopathology. 3rd ed. New York, NY: McGraw Hill Medical; 2010:362-38
  7. Hernández-Lugo AM, Domínguez-Cherit J, Vega-Memije ME. Digital mucoid cyst: the ganglion type. Int J Dermatol. 1999;38(7):533-555.
  8. Kim EJ, Huh JW, Park H-J. Digital mucous cyst: a clinical-surgical study. Ann Dermatol. 2017;29(1):69-73.
  9. Connolly M, de Berker DAR. Multiple myxoid cysts secondary to occupation. Clin Exp Dermatol. 2006;31(3):404-406.
  10. Goldman JA, Goldman L, Jaffe MS, Richfield DF. Digital mucinous pseudocysts. Arthritis Rheum. 1977;20(4):997-1002.
  11. Freire V, Guérini H, Campagna R, et al. Imaging of hand and wrist cysts: a clinical approach. AJR Am J Roentgenol. 2012;199(5):W618-W628.
  12. Balakirski G, Loeser C, Baron JM, Dippel E, Schmitt L. Effectiveness and safety of surgical excision in the treatment of digital mucoid cysts. Dermatol Surg. 2017;43(7):928-933.
  13. Epstein E. A simple technique for managing digital mucous cysts. Arch Dermatol. 1979;115(11):1315-1316.
  14. Weinheimer K, Patrick N, Darowish M. Treatment of distal interphalangeal ganglion cysts by volar corticosteroid injection [published online December 14, 2017]. Hand (N Y). doi:10.1177/1558944717744336.
  15. Lonsdale-Eccles AA, Langtry JAA. Treatment of digital myxoid cysts with infrared coagulation: a retrospective case series. Br J Dermatol. 2005;153(5):972-975.
  16. Karrer S, Hohenleutner U, Szeimies R-M, Landthaler M. Treatment of digital mucous cysts with a carbon dioxide laser. Acta Derm Venereol. 1999;79(3):224-225.
  17. Kim JH, Park JH, Jee H, Oh SH. Successful treatment of recurrent digital mucoid cysts using a 1,444-nm neodymium-doped yttrium aluminum garnet laser. Dermatol Surg. 2011;37(10):1528-1530.
  18. Esson GA, Holme SA. Treatment of 63 subjects with digital mucous cysts with percutaneous sclerotherapy using polidocanol. Dermatol Surg. 2016;42(1):59-62.
  19. Mesa-Álvarez L, Salgado-Boquete L, Flórez-Menéndez MÁ. An 18-month follow-up of digital myxoid cysts after therapy with percutaneous sclerotherapy with polidocanol. Dermatol Surg. 2018;44(1):140-142.
  20. Longhurst WD, Khachemoune A. An unknown mass: the differential diagnosis of digit tumors. Int J Dermatol. 2015;54(11):1214-1225.
  21. Marzuka AG, Book SE. Basal cell carcinoma: pathogenesis, epidemiology, clinical features, diagnosis, histopathology, and management. Yale J Biol Med. 2015;88(2):167-179.
  22. Prieto-Granada C, Rodriguez-Waitkus P. Cutaneous squamous cell carcinoma and related entities: epidemiology, clinical and histological features, and basic science overview. Curr Probl Cancer. 2015;39(4):206-215.
  23. Riddel C, Rashid R, Thomas V. Ungual and periungual human papillomavirus-associated squamous cell carcinoma: a review. J Am Acad Dermatol. 2011;64(6):1147-1153.
  24. Higgins HW II, Lee KC, Galan A, Leffell DJ. Melanoma in situ: part I. Epidemiology, screening, and clinical features. J Am Acad Dermatol. 2015;73(2):181-190.
  25. Li X, Yu J, Thomas S, Lee K, Soyer HP. Clinical and dermoscopic features of common warts. J Eur Acad Dermatol Venereol. 2017;31(7):e308-e310.
  26. Piraccini BM, Bellavista S, Misciali C, Tosti A, De Berker D, Richert B. Periungual and subungual pyogenic granuloma. Br J Dermatol. 2010;163(5):941-953.