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Congenital ectopic nail with bone deformity
British Journal of Plastic Surgery (1998), 51, 321–323 © 1998 The British Association of Plastic Surgeons
Congenital ectopic nail with bone deformity Y. Kamibayashi, S. Abe, T. Fujita, A. Imai, K. Komatsu and Y. Yamamoto Department of Plastic and Reconstructive Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan SUMMARY. This report describes two cases of congenital ectopic nail with bone deformity. Histologically, the squamous epithelium of the nail matrix lacked a definite granular layer. Resected nail tissue was connected with the periosteum of the tip of the ungual phalanx, which suggested that the contact of the ectopic nail matrix with the periosteum could impede intramembranous ossification and deform the bone shape.
that of the other fifth finger. The tip of the distal phalanx of the involved finger was flat, whereas that of the same finger on the other hand was round-shaped. The ectopic nail was surgically removed. As the nail bed contacted the distal phalanx, the connecting periosteum was resected. Histological examination (Fig. 3) demonstrated that weakly eosin-stained thick stratified tissue and strongly eosin-stained tissue were present. The squamous epithelium beneath the faintly eosin-stained stratified tissue lacked definite granular layers, implying that this tissue was nail matrix. After surgical resection of this ectopic nail, there has been no recurrence for more than 2 years.
Congenital ectopic nail is an extremely rare deformity. Fewer than 20 cases have been reported previously. In most cases these abnormal nails are found on the palmar surface of the fifth finger, although the bone deformity is occasionally present on the ungual phalanx of involved digit. Histologically, the ectopic nail matrix is similar to the normal nail matrix. The aetiology is considered to be a teratoma or hamartoma – the ectopic presence of stray germ cells. This report describes two cases of congenital ectopic nail with bone deformity. Case report
Case 2
Case 1 A 6-year-old girl had a small ectopic nail on the palmar surface of the tip of her left fifth finger (Fig. 1). This ectopic nail had been present since birth, and grew at the same rate as the other normal nails. The patient sometimes cut this nail because of pain and irritation. Her family history was noncontributory and she had no other malformation. X-rays (Fig. 2) revealed that the shape of the distal phalanx of the affected left fifth finger was different from
A 4-year-old boy had since birth a small ectopic nail on the palmar side of the tip of his right fifth finger (Fig. 4). It grew at the same rate as the other nails. His family history was non-contributory. There were no other congenital abnormalities. X-ray examination demonstrated that the tip of the distal phalanx of the affected right finger was inverted, whereas that of the same finger on the other hand was round-shaped (Fig. 5).
Fig. 1
Fig. 2
Figure 1—Case 1: The small ectopic nail, indicated by an arrow, is visible on palmar side of the left fifth finger. Figure 2—Case 1: X-ray photographs. (left) The tip of the left fifth distal phalanx is flat (arrow). (right) The tip of the right fifth distal phalanx is round-shaped (arrow).
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Fig. 3 Figure 3—Case 1: Histological features of the removed ectopic nail. (left) The thick stratified tissue is composed of faintly eosin-stained tissue and deeply eosin-stained tissue (× 35). (right) The squamous epithelium beneath the faintly eosin-stained stratified tissue lacks a fine granular layer (× 170).
Fig. 4
Fig. 5
Figure 4—Case 2: The small ectopic nail, indicated by an arrow, on the right fifth finger. Figure 5—Case 2: X-ray photograph. (left) The tip of the left fifth distal phalanx is round-shaped (arrow). (right) The tip of the right fifth distal phalanx is flat (arrow).
The ectopic nail was surgically removed. As the nail bed was situated on the distal phalanx, we resected the connecting periosteum. Since surgery, there has been no recurrence for more than 1 year.
Discussion Congenital ectopic nail is a rare disorder of fingers and toes. There have been fewer than 20 cases of this deformity reported. All previous reported congenital ectopic nails were situated on the palmar surface of the fifth finger except the cases of Kikuchi et al1 (right third finger, dorsal side), Aoki and Suzuki2 (right second toe, dorsal side), and Markinson et al3 (right third toe, dorsal side). Similarly, our cases occurred on the palmar surface of the fifth finger. With respect to the frequent finding on the fifth finger, this anomaly is in accordance with rudimentary polydactyly.4 Baden et al5 described a congenital clawlike structure at the end of the fifth finger not as
congenital ectopic nail but as rudimentary polydactyly. However, they did not show the result of histological examination and only commented that it was a papilloma with a hyperkeratotic surface. It is unclear whether their example was a rudimentary polydactyly because of the lack of description of the Meissner body and nerve bundle. It is generally accepted that a Meissner body and nerve bundle are detected in rudimentary polydactyly.4 Some cases were examined by radiography of involved fingers or toes. Our cases are consistent with those of Yamasaki et al6 and Miura,7 who demonstrated deformity at the involved ungual phalanx via X-ray photographs, whereas other cases showed a normal phalanx. The most probable explanations for the discrepancy are the differences of the depth and position of the ectopic nail matrix. The nail matrix of our cases was situated on the distal end of the ungual phalanx of the involved finger and contacted its periosteum, as in the case of Yamasaki et al.6 Miura7 did not describe the nail matrix because he did not
Congenital ectopic nail with bone deformity
operate. It is known that the ungual phalanx possesses three ossification centers, the distal end, the mid-shaft, and the base. The ossification of the distal end is intramembranous, whereas the other two are intracartilaginous ossification. The contact of the nail matrix with the ungual phalanx periosteum could impede intramembranous ossification and deform the bone shape. All the cases with histological examination showed an ectopic nail matrix without a fine granular layer. By electron microscopy, Aoki and Suzuki2 showed spherical keratohyalin granules in the uppermost layers of the ectopic nail matrix, suggesting that the ectopic nail matrix bears structural similarity to the normal nail matrix. A study by Aoki and Hataba8 demonstrated the amino-acid composition of congenital ectopic nail. The amino-acid analysis revealed that 17 kinds of amino acids in the ectopic nail were different from those seen in the normal nail. This suggested that an ectopic nail is not merely a smaller version of a normal nail. The pathogenesis of this abnormality has not been clarified. However, two possible causes for this anomaly have been hypothesised. One is that it might develop from stray germ cells1,6,9 (i.e. a teratoma or hamartoma). Another is that it might be a kind of rudimentary polydactyly.10 We consider that the former is more probable because we could not find anything in the literature which clearly showed a Meissner body and nerve bundle.
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References 1. Kikuchi I, Ono T, Ogata K. Ectopic nail: case reports. Plast Reconstr Surg 1978; 61: 781–3. 2. Aoki K, Suzuki H. The morphology and hardness of the nail in two cases of congenital onychoheterotopia. Br J Dermatol 1984; 110: 717–23. 3. Markinson B, Brenner AR, McGrath M. Congenital ectopic nail. A case study. J Amer Pod Med Ass 1988; 78: 318–9. 4. Shapiro L, Juhlin EA, Brownstein MH. ‘Rudimentary polydactyly’ an amputation neuroma. Arch Dermatol 1973; 108: 223–5 5. Baden HP, Alper JC, Lee LD. Rudimentary polydactyly presenting as a claw. Arch Dermatol 1976; 112: 1006–7. 6. Yamasaki R, Yamasaki M, Kokoroishi T, Jidoi J. Ectopic nail associated with bone deformity. J Dermatol 1984; 11: 295–300. 7. Miura T. Two families with congenital nail anomalies: Nail formation in ectopic areas. J Hand Surg 1978; 3: 348–51. 8. Aoki K, Hataba Y. A case of congenital onychoheterotopia on both fifth fingers. Clin Exp Dermatol 1991; 16: 285–6 9. Katayama I, Maeda M, Nishioka K. Congenital ectopic nail of the fifth finger. Br J Dermatol 1984; 111: 231–3. 10. Rider MA. Congenital palmar nail syndrome. J Hand Surg 1992; 17B: 371–2.
The Authors Yoshihito Kamibayashi, MD Seishu Abe, MD Tatsuya Fujita, MD Akihito Imai, MD Kiyoshi Komatsu, MD Yoshiteru Yamamoto, MD Department of Plastic and Reconstructive Surgery, Sapporo Medical University School of Medicine, S-1, W-16, Chuo-ku, Sapporo 060, Japan. Correspondence to: Dr Yoshihito Kamibayashi
Acknowledgement We thank Mr K. Barrymore for advice on English usage.
Paper received 6 June 1997. Accepted 10 March 1998.
Congenital ectopic nail with bone deformity Y. Kamibayashi, S. Abe, T. Fujita, A. Imai, K. Komatsu and Y. Yamamoto Department of Plastic and Reconstructive Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan SUMMARY. This report describes two cases of congenital ectopic nail with bone deformity. Histologically, the squamous epithelium of the nail matrix lacked a definite granular layer. Resected nail tissue was connected with the periosteum of the tip of the ungual phalanx, which suggested that the contact of the ectopic nail matrix with the periosteum could impede intramembranous ossification and deform the bone shape.
that of the other fifth finger. The tip of the distal phalanx of the involved finger was flat, whereas that of the same finger on the other hand was round-shaped. The ectopic nail was surgically removed. As the nail bed contacted the distal phalanx, the connecting periosteum was resected. Histological examination (Fig. 3) demonstrated that weakly eosin-stained thick stratified tissue and strongly eosin-stained tissue were present. The squamous epithelium beneath the faintly eosin-stained stratified tissue lacked definite granular layers, implying that this tissue was nail matrix. After surgical resection of this ectopic nail, there has been no recurrence for more than 2 years.
Congenital ectopic nail is an extremely rare deformity. Fewer than 20 cases have been reported previously. In most cases these abnormal nails are found on the palmar surface of the fifth finger, although the bone deformity is occasionally present on the ungual phalanx of involved digit. Histologically, the ectopic nail matrix is similar to the normal nail matrix. The aetiology is considered to be a teratoma or hamartoma – the ectopic presence of stray germ cells. This report describes two cases of congenital ectopic nail with bone deformity. Case report
Case 2
Case 1 A 6-year-old girl had a small ectopic nail on the palmar surface of the tip of her left fifth finger (Fig. 1). This ectopic nail had been present since birth, and grew at the same rate as the other normal nails. The patient sometimes cut this nail because of pain and irritation. Her family history was noncontributory and she had no other malformation. X-rays (Fig. 2) revealed that the shape of the distal phalanx of the affected left fifth finger was different from
A 4-year-old boy had since birth a small ectopic nail on the palmar side of the tip of his right fifth finger (Fig. 4). It grew at the same rate as the other nails. His family history was non-contributory. There were no other congenital abnormalities. X-ray examination demonstrated that the tip of the distal phalanx of the affected right finger was inverted, whereas that of the same finger on the other hand was round-shaped (Fig. 5).
Fig. 1
Fig. 2
Figure 1—Case 1: The small ectopic nail, indicated by an arrow, is visible on palmar side of the left fifth finger. Figure 2—Case 1: X-ray photographs. (left) The tip of the left fifth distal phalanx is flat (arrow). (right) The tip of the right fifth distal phalanx is round-shaped (arrow).
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Fig. 3 Figure 3—Case 1: Histological features of the removed ectopic nail. (left) The thick stratified tissue is composed of faintly eosin-stained tissue and deeply eosin-stained tissue (× 35). (right) The squamous epithelium beneath the faintly eosin-stained stratified tissue lacks a fine granular layer (× 170).
Fig. 4
Fig. 5
Figure 4—Case 2: The small ectopic nail, indicated by an arrow, on the right fifth finger. Figure 5—Case 2: X-ray photograph. (left) The tip of the left fifth distal phalanx is round-shaped (arrow). (right) The tip of the right fifth distal phalanx is flat (arrow).
The ectopic nail was surgically removed. As the nail bed was situated on the distal phalanx, we resected the connecting periosteum. Since surgery, there has been no recurrence for more than 1 year.
Discussion Congenital ectopic nail is a rare disorder of fingers and toes. There have been fewer than 20 cases of this deformity reported. All previous reported congenital ectopic nails were situated on the palmar surface of the fifth finger except the cases of Kikuchi et al1 (right third finger, dorsal side), Aoki and Suzuki2 (right second toe, dorsal side), and Markinson et al3 (right third toe, dorsal side). Similarly, our cases occurred on the palmar surface of the fifth finger. With respect to the frequent finding on the fifth finger, this anomaly is in accordance with rudimentary polydactyly.4 Baden et al5 described a congenital clawlike structure at the end of the fifth finger not as
congenital ectopic nail but as rudimentary polydactyly. However, they did not show the result of histological examination and only commented that it was a papilloma with a hyperkeratotic surface. It is unclear whether their example was a rudimentary polydactyly because of the lack of description of the Meissner body and nerve bundle. It is generally accepted that a Meissner body and nerve bundle are detected in rudimentary polydactyly.4 Some cases were examined by radiography of involved fingers or toes. Our cases are consistent with those of Yamasaki et al6 and Miura,7 who demonstrated deformity at the involved ungual phalanx via X-ray photographs, whereas other cases showed a normal phalanx. The most probable explanations for the discrepancy are the differences of the depth and position of the ectopic nail matrix. The nail matrix of our cases was situated on the distal end of the ungual phalanx of the involved finger and contacted its periosteum, as in the case of Yamasaki et al.6 Miura7 did not describe the nail matrix because he did not
Congenital ectopic nail with bone deformity
operate. It is known that the ungual phalanx possesses three ossification centers, the distal end, the mid-shaft, and the base. The ossification of the distal end is intramembranous, whereas the other two are intracartilaginous ossification. The contact of the nail matrix with the ungual phalanx periosteum could impede intramembranous ossification and deform the bone shape. All the cases with histological examination showed an ectopic nail matrix without a fine granular layer. By electron microscopy, Aoki and Suzuki2 showed spherical keratohyalin granules in the uppermost layers of the ectopic nail matrix, suggesting that the ectopic nail matrix bears structural similarity to the normal nail matrix. A study by Aoki and Hataba8 demonstrated the amino-acid composition of congenital ectopic nail. The amino-acid analysis revealed that 17 kinds of amino acids in the ectopic nail were different from those seen in the normal nail. This suggested that an ectopic nail is not merely a smaller version of a normal nail. The pathogenesis of this abnormality has not been clarified. However, two possible causes for this anomaly have been hypothesised. One is that it might develop from stray germ cells1,6,9 (i.e. a teratoma or hamartoma). Another is that it might be a kind of rudimentary polydactyly.10 We consider that the former is more probable because we could not find anything in the literature which clearly showed a Meissner body and nerve bundle.
323
References 1. Kikuchi I, Ono T, Ogata K. Ectopic nail: case reports. Plast Reconstr Surg 1978; 61: 781–3. 2. Aoki K, Suzuki H. The morphology and hardness of the nail in two cases of congenital onychoheterotopia. Br J Dermatol 1984; 110: 717–23. 3. Markinson B, Brenner AR, McGrath M. Congenital ectopic nail. A case study. J Amer Pod Med Ass 1988; 78: 318–9. 4. Shapiro L, Juhlin EA, Brownstein MH. ‘Rudimentary polydactyly’ an amputation neuroma. Arch Dermatol 1973; 108: 223–5 5. Baden HP, Alper JC, Lee LD. Rudimentary polydactyly presenting as a claw. Arch Dermatol 1976; 112: 1006–7. 6. Yamasaki R, Yamasaki M, Kokoroishi T, Jidoi J. Ectopic nail associated with bone deformity. J Dermatol 1984; 11: 295–300. 7. Miura T. Two families with congenital nail anomalies: Nail formation in ectopic areas. J Hand Surg 1978; 3: 348–51. 8. Aoki K, Hataba Y. A case of congenital onychoheterotopia on both fifth fingers. Clin Exp Dermatol 1991; 16: 285–6 9. Katayama I, Maeda M, Nishioka K. Congenital ectopic nail of the fifth finger. Br J Dermatol 1984; 111: 231–3. 10. Rider MA. Congenital palmar nail syndrome. J Hand Surg 1992; 17B: 371–2.
The Authors Yoshihito Kamibayashi, MD Seishu Abe, MD Tatsuya Fujita, MD Akihito Imai, MD Kiyoshi Komatsu, MD Yoshiteru Yamamoto, MD Department of Plastic and Reconstructive Surgery, Sapporo Medical University School of Medicine, S-1, W-16, Chuo-ku, Sapporo 060, Japan. Correspondence to: Dr Yoshihito Kamibayashi
Acknowledgement We thank Mr K. Barrymore for advice on English usage.
Paper received 6 June 1997. Accepted 10 March 1998.