Growths on the fingers

Growths on the fingers

CASE #1

A skin exam of a black woman aged 45 years revealed papules on the outside of her pinkies. According to the patient, the papules had been present since birth and did not bother her. She also stated that they had not changed in size since childhood.

An x-ray of the lesion revealed that these nubbins of flesh, containing no bone. The woman stated that to the best of her knowledge, neither her parents nor her brother and two sisters had similar lesions. Her three children had no lesions that resembled hers, either.

CASE #2

A man aged 40 years presented with a six-month history of a growth on the side of one middle finger. The lesion did not itch, burn, or hurt. OTC wart treatments had no affect. The patient was not taking any medication and had no history of any systemic disease.

The lesion was removed by a shave excision. Histologic examination showed a dermal core composed of thick, closely intertwined collagen bundles with numerous capillaries, varying numbers of fibroblasts, and thin elastic fibers oriented along the vertical axis of the lesion.

What is the diagnosis?

For CASE #1, click "NEXT." For CASE #2, click "3."

CASE #1: Accessory digits

An accessory digit most commonly appears as a solitary finding. This patient was most likely a case of autosomal dominant disease with incomplete penetrance (only about 30% of patients will have a positive family history for polydactyly or sporadic inheritance). Duplications occur bilaterally in about 40%-50% of patients, but these are often not symmetric.

Extra digits occur most commonly on the ulnar side of the hand (postaxial polydactyly), less commonly on the radial side (preaxial polydactyly), and very rarely on one of the middle three digits (central polydactyly).^2,3 Central polydactyly is often inherited with an associated syndactyly, a condition in which two or more digits are fused together. The extra digit is most commonly an abnormal fork of one of the five digits. Rarely, the extra digit may originate at the wrist as a normal digit does.

Polydactyly is a finding of 267 syndromes listed in Online Mendelian Inheritance in Man (available at www.ncbi.nlm.nih.gov/omim, accessed July 15, 2011), a database of human genes and genetic disorders, and syndromic polydactyly is commonly an autosomal recessively inherited trait.⁴ Because hand and foot polydactyly are associated with congenital defects in 23.4% of patients, a genetic workup and thorough medical examination should be performed in these patients.

A number of syndromes include polydactyly as a finding: acrocallosal syndrome, basal cell nevus syndrome, Bardet-Biedl syndrome, Biemond syndrome, ectrodactyly-ectodermal dysplasia-cleft lip/palate syndrome, Ellis van Creveld syndrome, Hirschsprung disease, unilateral renal agenesis, hypertelorism, congenital deafness, Meckel Gruber syndrome, Joubert-Boltshauser syndrome, Laurin-Sandrow syndrome, McKusick-Kaufman syndrome, mirror hand deformity (ulnar dimelia), Mohr syndrome, oral-facial-digital syndrome, Pallister-Hall syndrome, Rubinstein-Taybi syndrome, Smith-Lemli-Opitz syndrome, short rib polydactyly, trisomy 13 and 21, tibial hemimelia, VATER association (Vertebral [defects], [imperforate] Anus, Tracheoesophageal [fistula], Radial and renal [dysplasia]).⁵

Polydactyly has an incidence of one in every 500-1,000 live births. Postaxial hand polydactyly is a common isolated disorder in African black and African-American children, and autosomal dominant transmission is the likely mode of inheritance. Postaxial polydactyly is approximately 10 times more frequent in blacks than in whites and is more frequent in male children. Among blacks, polydactyly occurs in about four of 1,000 births, compared with 0.3 to 1.3 out of 1,000 births among whites. Polydactyly appears to be slightly more common in males. In contrast, postaxial polydactyly seen in white children is usually syndromic and associated with an autosomal recessive transmission.

Diagnosis of polydactyly can be made in utero with ultrasound. A radiologist can identify fetal finger buds utilizing transvaginal ultrasound as early as 9 weeks' and reliably by 13 weeks' gestation.^6,7 If polydactyly is noted, conduct a through examination of the heart, nervous system, limbs, and kidneys to identify associated syndromes. Skeletal dysplasias can be linked to polydactyly (i.e., short rib polydactyly). Follow-up ultrasound between 17-34 weeks with biometric profile can establish the diagnosis of isolated polydactyly.

Histologic examination postaxial or preaxial nubbin tissue resembles the histology of a congenital traumatic neuroma and demonstrates hyperkeratosis and acanthosis overlying many nerve bundles in the dermis. Abundant Merkel cells⁸ 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.⁹

If a type I polydactyly is present at birth and x-ray shows no bone in the post-axial duplicated digit, the postaxial nubbin can be removed through suture ligation in the newborn nursery. It should be noted that suture ligation is not usually performed in older infants.^10-12 Suture ligation of supernumerary digits with residual cartilage and/or an underlying duplicated metatarsal will lead to future deformity.¹³ If type II or type III polydactyly is present, a surgeon can perform formal amputation after x-rays are taken to ensure that there are no underlying deformed metatarsals, in which case the supranumerary digit should be surgically excised. Postponing excision until age 9 to 12 months is advisable to decrease anesthesia risk. Adequate web space should be preserved and the digit removed.

As the digits did not affect the health of the patient, it was decided to leave them in place. A complete physical showed no systemic findings related to the accessory digits.

CASE #2: Acquired digital fibrokeratomas

Acquired digital fibrokeratomas (ADFKs) are uncommon skin neoplasms that manifest as asymptomatic, solitary, smooth, dome-shaped, flesh-colored papules or nodules, usually with a collarette at the base creating a moatlike configuration at their bottom.

These growths are usually solitary, but multiple lesions have rarely been reported. Most ADFKs measure 0.5 to 1.5 cm in height or diameter, but larger growths with a diameter or height greater than 3 cm have been noted. ADFKs develop most commonly on the fingers and toes. A number of cases have been noted on the heel. A few patients with ADFKs occurring on the elbow, wrist, calf, and the prepatellar area have been seen.

The epidemiology of ADFKs is not well defined. ADFKs are most common in men, but the paucity of reports makes a true sexual predilection difficult to establish. ADFKs most commonly arise in middle age, with reported ages of onset ranging from 12 to 70 years (average age 40 years). No racial predilection has been noted.

Investigators first described ADFKs in 1968 in a series of 10 patients with hand lesions.¹⁴ Later that year, investigators noted 28 cases of similar lesions, with some occurring on the arms and legs and suggested that "acquired acral fibrokeratoma" would be a more accurate description.¹⁵

The differential diagnosis of ADFKs includes: corn, superficial acral fibromyxoma, aggressive digital papillary adenocarcinoma, squamous cell carcinoma (in particular, subungual keratoacanthoma), osteoma, cutaneous horn, verruca vulgaris, supernumerary digit, Koenen's tumor (periungual fibromas), pyogenic granuloma (lobular capillary hemangioma), acrochordon, infantile digital fibromatosis, and neurofibroma.

Papules or nodules that arise before puberty and fit the description of ADFKs are most likely supernumerary digits. Supernumerary digits occur on the proximal portion of the fifth digit and are made up of abundant nerve bundles. Unlike an ADFK, an acquired periungual fibrokeratoma arises from the proximal nail fold. Although similar in appearance to ADFKs, Koenen's tumors occur in association with tuberous sclerosis and possess atypical stellate myofibroblasts. Aggressive digital papillary adenocarcinoma, which can be fatal, is the most important condition to exclude from ADFK.

The cause of ADFKs is unknown. While researchers point toward trauma or repetitive irritation, there may be an unknown genetic factor at work. The conditions that most closely resemble ADFKs—supernumerary digits and the periungual fibromas of tuberous sclerosis—have a genetic basis. Reports of ADFKs occurring with a pyogenic granuloma buttresses the idea that trauma relates to their etiology.¹⁶

The histology of ADFK is well described. The lesion manifests as a small, well-circumscribed, dome-shaped or narrow elongated papule. The stratum corneum is usually hyperkeratotic, with the hyperkeratosis greatest at the top of the ADFK. An acanthotic epidermis with slightly attenuated or elongated rete ridges is typically found.

The dermal core of an ADFK demonstrates three possible histological patterns.^14,17 The most common, type I, consists of a dermal core composed of thick, closely intertwined collagen bundles with numerous capillaries, varying numbers of fibroblasts, and thin elastic fibers oriented along the vertical axis of the lesion.

Type II ADFKs resemble type I but also possess many more fibroblasts arranged in fascicles and greatly reduced numbers of elastic fibers. Type III ADFKs are the least common and possess a dermal core that is poorly cellular and edematous with a reduced number of elastic fibers.

Interestingly, cyclosporine (Gengraf, Neoral, Sandimmune) has been linked to the development of ADFKs.¹⁸ Acquired periungual fibrokeratoma developing after acute staphylococcal paronychia has been noted as well.¹⁹

ADFK treatment is not complex. Unlike warts, ADFKs cannot be treated with cryotherapy.²⁰ These lesions are usually just a cosmetic problem, and no cases of malignant transformation have been reported. Occurrence in locations at which pressure is constant (e.g., the dorsum or plantar surface of the foot) can cause pain. In such cases, removal has a medical rather than a cosmetic basis. Removal with a shave or simple surgical excision is curative, with recurrence after surgery unlikely. Six months after removal of this patient's lesion, it had not recurred.

Noah S. Scheinfeld, MD, JD, is assistant clinical professor of dermatology at Columbia University in New York City, where he has a private practice. The author has no relationships to disclose relating to the content of this article.

References

1. Hosalkar HS, Shah H, Gujar P, Kulkarni AD. Crossed polydactyly. J Postgrad Med. 1999;45:90-92.

2. Cohen MS. Thumb duplication. Hand Clin. 1998;14:17-27.

3. Hung L, Cheng JC, Bundoc R, Leung P. Thumb duplication at the metacarpophalangeal joint. Management and a new classification. Clin Orthop Relat Res. 1996;323:31-41.

4. Temtamy SA, McKusick VA. The genetics of hand malformations. Birth Defects Orig Artic Ser. 1978;14:i-xviii, 1-619.

5. Castilla EE, Lugarinho R, da Graça Dutra M, Salgado LJ. Associated anomalies in individuals with polydactyly. Am J Med Genet. 1998;80:459-465.

6. Bromley B, Shipp TD, Benacerraf B. Isolated polydactyly: prenatal diagnosis and perinatal outcome. Prenat Diagn. 2000;20:905-908.

7. Zimmer EZ, Bronshtein M. Fetal polydactyly diagnosis during early pregnancy: clinical applications. Am J Obstet Gynecol. 2000;183:755-758.

8. Ban M, Kitajima Y. The number and distribution of Merkel cells in rudimentary polydactyly. Dermatology. 2001;202:31-34.

9. Shapiro L, Juhlin EA, Brownstein MH. "Rudimentary polydactyly": an amputation neuroma. Arch Dermatol. 1973;108:223-225.

10. Morley SE, Smith PJ. Polydactyly of the feet in children: suggestions for surgical management. Br J Plast Surg. 2001;54:34-38.

11. Graham TJ, Ress AM. Finger polydactyly. Hand Clin. 1998;14:49-64.

12. Hare PJ. Rudimentary polydactyly. Br J Dermatol. 1954;66:402-408.

13. Heras L, Barco J, Cohen A. Unusual complication of ligation of rudimentary ulnar digit. J Hand Surg Br. 1999;24:750-751.

14. Bart RS, Andrade R, Kopf AW, Leider M. Acquired digital fibrokeratomas. Arch Dermatol. 1968;97:120-129.

15. Pinkus H. Discussion—acquired digital fibrokeratoma. Arch Dermatol. 1968;97:128-129.

16. Lee DR, Lee JY, Ahn JY, Park MY. A case of acquired digital fibrokeratoma accompanied by pyogenic granuloma. Dermatol Online J. 2009;15:8.

17. Kint A, Baran R. Histopathologic study of Koenen tumors. Are they different from acquired digital fibrokeratoma? J Am Acad Dermatol. 1988;18:369-372.

18. Qiao J, Liu YH, Fang K. Acquired digital fibrokeratoma associated with ciclosporin treatment. Clin Exp Dermatol. 2009;34:257-259.

19. Sezer E, Bridges AG, Koseoglu D, Yuksek J. Acquired periungual fibrokeratoma developing after acute staphylococcal paronychia. Eur J Dermatol. 2009;19:636-637.

20. Frydman AF, Mercer SE, Kleinerman R, et al. Acquired fibrokeratoma presenting as multiple plantar nodules. Dermatol Online J. 2010;16:5.

All electronic documents accessed July 15, 2011.