eMedicine Specialties > Dermatology > Pediatric Diseases

Supernumerary Digit: Differential Diagnoses & Workup

Author: Carter G Abel, MD, Clinical Assistant Attending, Department of Dermatology, New York Presbyterian Hospital
Coauthor(s): Denise M McCarthy, MD, Associate Professor, Department of Radiology, Morristown Memorial Hospital
Contributor Information and Disclosures

Updated: Jul 31, 2008

Differential Diagnoses

Down Syndrome

Other Problems to Be Considered

Several dozen syndromes have been identified that include polydactyly as associated clinical manifestations. Among these are the following:

Acrocallosal syndrome
Basal cell nevus syndrome
Bardet-Biedl syndrome
Biemond syndrome
Ectrodactyly-ectodermal dysplasias-cleft lip/palate syndrome
Ellis van Creveld syndrome
Meckel Gruber syndrome
McKusick-Kaufman syndrome
Mirror hand deformity (ulnar dimelia)8
Mohr syndrome
Oral-facial-digital syndrome
Pallister-Hall syndrome
Rubinstein-Taybi syndrome
Short rib polydactyly
VATER association (vertebral [defects], [imperforate] anus, tracheoesophageal [fistula], radial and renal [dysplasia])

Workup

Laboratory Studies

  • Because hand and foot polydactyly are associated with congenital defects in 23.4% of patients, genetic workup and thorough medical examination in these patients is recommended.
    • Polydactyly rarely is associated with congenital anomalies, except in recognizable syndromes. In one study by Castilla et al,9 trisomy 13, Meckel syndrome, and Down syndrome accounted for most cases of polydactyly.
    • Other associated syndromes include cerebellar vermis aplasia with features suggesting Meckel syndrome and Smith-Lemli-Opitz syndrome, Jeune syndrome, short rib-polydactyly syndromes (Saldino-Noonan syndrome and Majewski types), Ellis-van Creveld syndrome, acrocephalopolydactylous dysplasia, Bardet-Biedl (types 2 and 3), and trisomy (13-15). Down syndrome was associated strongly with duplication of the first digit.
  • In addition, the incidence of postaxial polydactyly is less common in whites, suggesting that a systemic workup should be considered.

Imaging Studies

  • Prenatal ultrasound10,11
    • Fetal finger buds can be seen using transvaginal ultrasound as early as 9 weeks and reliably by 13 weeks of pregnancy.
    • Once polydactyly is established, a thorough ultrasound evaluation, especially of the heart, nervous system, limbs, and kidneys, to identify an associated syndrome, such as Meckel Gruber syndrome and trisomy 13, should be performed.
    • Skeletal dysplasias also may cause polydactyly, such as short rib polydactyly. Follow-up ultrasound between 17-34 weeks with biometric profile is recommended to establish the diagnosis of isolated polydactyly. Skeletal dysplasias also may affect the hand, for instance, hitchhiker thumb in diastrophic dysplasia or polydactyly in short rib polydactyly. Isolated polydactyly has a good prognosis.
  • Radiographs
    • Radiographs of the affected limb are recommended to show whether the rudimentary digit contains skeletal elements.
    • The degree of deviation of the digit and the size of the articulating metacarpal or metatarsal also may be helpful in surgical planning.

Histologic Findings

Rudimentary polydactyly, which may be a type of congenital traumatic neuroma, shows hyperkeratosis and acanthosis overlying many nerve bundles in the dermis. It may appear as a papule on the base of the ulnar side of the little finger. Abundant Merkel cells may appear at first and then disappear after the development of these nerve bundles, which form Meissner corpuscles in the dermal papillae and stain positively with S-100 protein.12

More on Supernumerary Digit

Overview: Supernumerary Digit
Differential Diagnoses & Workup: Supernumerary Digit
Treatment & Medication: Supernumerary Digit
Follow-up: Supernumerary Digit
References
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References

  1. Hosalkar HS, Shah H, Gujar P, Kulkarni AD. Crossed polydactyly. J Postgrad Med. Jul-Sep 1999;45(3):90-2. [Medline].

  2. Muragaki Y, Mundlos S, Upton J, Olsen BR. Altered growth and branching patterns in synpolydactyly caused by mutations in HOXD13. Science. Apr 26 1996;272(5261):548-51. [Medline].

  3. Finley WH, Gustavson KH, Hall TM, Hurst DC, Barganier CM, Wiedmeyer JA. Birth defects surveillance: Jefferson County, Alabama, and Uppsala County, Sweden. South Med J. Apr 1994;87(4):440-5. [Medline].

  4. Cohen MS. Thumb duplication. Hand Clin. Feb 1998;14(1):17-27. [Medline].

  5. Hung L, Cheng JC, Bundoc R, Leung P. Thumb duplication at the metacarpophalangeal joint. Management and a new classification. Clin Orthop Relat Res. Feb 1996;31-41. [Medline].

  6. Temtamy SA, McKusick VA. The genetics of hand malformations. Birth Defects Orig Artic Ser. 1978;14(3):i-xviii, 1-619. [Medline].

  7. Malik S, Grzeschik KH. Synpolydactyly: clinical and molecular advances. Clin Genet. Feb 2008;73(2):113-20. [Medline].

  8. Jafari D, Sharifi B. A variant of mirror hand. A case report. J Bone Joint Surg Br. Jan 2005;87(1):108-10. [Medline].

  9. Castilla EE, Lugarinho R, da Graça Dutra M, Salgado LJ. Associated anomalies in individuals with polydactyly. Am J Med Genet. Dec 28 1998;80(5):459-65. [Medline].

  10. Bromley B, Shipp TD, Benacerraf B. Isolated polydactyly: prenatal diagnosis and perinatal outcome. Prenat Diagn. Nov 2000;20(11):905-8. [Medline].

  11. Zimmer EZ, Bronshtein M. Fetal polydactyly diagnosis during early pregnancy: clinical applications. Am J Obstet Gynecol. Sep 2000;183(3):755-8. [Medline].

  12. Ban M, Kitajima Y. The number and distribution of Merkel cells in rudimentary polydactyly. Dermatology. 2001;202(1):31-4. [Medline].

  13. Morley SE, Smith PJ. Polydactyly of the feet in children: suggestions for surgical management. Br J Plast Surg. Jan 2001;54(1):34-8. [Medline].

  14. Eskandari MM, Oztuna V, Demirkan F. Late psychosocial effects of congenital hand anomaly. Hand Surg. Dec 2004;9(2):257-9. [Medline].

  15. Al-Aithan B, Al-Blaihed L, Mahmoud S, Hassanain J, Al-Qattan MM. Thumb polydactyly with symphalangism. J Hand Surg [Br]. Aug 2005;30(4):346-9. [Medline].

  16. Castilla EE, da Graca Dutra M, Lugarinho da Fonseca R, Paz JE. Hand and foot postaxial polydactyly: two different traits. Am J Med Genet. Nov 28 1997;73(1):48-54. [Medline].

  17. Cavalcanti DP, Salomão MA. Dandy-Walker malformation with postaxial polydactyly: further evidence for autosomal recessive inheritance. Am J Med Genet. Jul 16 1999;85(2):183-4. [Medline].

  18. Chiang H, Huang SC. Polydactyly of the foot: manifestations and treatment. J Formos Med Assoc. Mar 1997;96(3):194-8. [Medline].

  19. Chung J, Nam IW, Ahn SK, Lee SH, Kim JG, Sung YO. Rudimentary polydactyly. J Dermatol. Jan 1994;21(1):54-5. [Medline].

  20. Cummins H. Spontaneous amputation of human supernumerary digits: pedunculated postminimi. Am J Anat. 1932;51:381-416.

  21. Graham TJ, Ress AM. Finger polydactyly. Hand Clin. Feb 1998;14(1):49-64. [Medline].

  22. Hare PJ. Rudimentary polydactyly. Br J Dermatol. Nov 1954;66(11):402-8. [Medline].

  23. Heras L, Barco J, Cohen A. Unusual complication of ligation of rudimentary ulnar digit. J Hand Surg [Br]. Dec 1999;24(6):750-1. [Medline].

  24. Manske PR. Subclassification of polydactyly. Br J Plast Surg. Mar 1996;49(2):137. [Medline].

  25. Sergi C, Adam S, Kahl P, Otto HF. Study of the malformation of ductal plate of the liver in Meckel syndrome and review of other syndromes presenting with this anomaly. Pediatr Dev Pathol. Nov-Dec 2000;3(6):568-83. [Medline].

  26. Shapiro L, Juhlin EA, Brownstein MH. "Rudimentary polydactyly": an amputation neuroma. Arch Dermatol. Aug 1973;108(2):223-5. [Medline].

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Further Reading

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Keywords

rudimentary polydactyly, digital duplication, hand anomaly, synpolydactyly

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Contributor Information and Disclosures

Author

Carter G Abel, MD, Clinical Assistant Attending, Department of Dermatology, New York Presbyterian Hospital
Carter G Abel, MD is a member of the following medical societies: American Academy of Dermatology, American College of Mohs Micrographic Surgery and Cutaneous Oncology, American Society for Dermatologic Surgery, and Medical Society of New Jersey
Disclosure: Nothing to disclose.

Coauthor(s)

Denise M McCarthy, MD, Associate Professor, Department of Radiology, Morristown Memorial Hospital
Denise M McCarthy, MD is a member of the following medical societies: American Association for Women Radiologists, American Roentgen Ray Society, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

Medical Editor

Albert C Yan, MD, Section Chief, Associate Professor, Department of Pediatrics, Section of Dermatology, Children's Hospital of Philadelphia and University of Pennsylvania
Albert C Yan, MD is a member of the following medical societies: American Academy of Dermatology, American Academy of Pediatrics, Society for Investigative Dermatology, and Society for Pediatric Dermatology
Disclosure: Nothing to disclose.

Pharmacy Editor

Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University School of Medicine; Consulting Staff, Mountain View Dermatology, PA
Richard P Vinson, MD is a member of the following medical societies: American Academy of Dermatology, Association of Military Dermatologists, Texas Dermatological Society, and Texas Medical Association
Disclosure: Nothing to disclose.

Managing Editor

Robert A Schwartz, MD, MPH, Professor and Head of Dermatology, Professor of Medicine, Professor of Pediatrics, Professor of Pathology, Professor of Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School
Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and Sigma Xi
Disclosure: Nothing to disclose.

CME Editor

Glen H Crawford, MD, Assistant Clinical Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Chief, Division of Dermatology, The Pennsylvania Hospital
Glen H Crawford, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, Phi Beta Kappa, and Society of USAF Flight Surgeons
Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology
Disclosure: Nothing to disclose.

 
 
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