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An epidermoid cyst of the tendon
An epidermoid cyst of the tendon An epidermoid cyst in the flexor superficialis tendon of the right middle finger of a child limited extension of the finger by preventing the distal gliding of the tendon at the inlet of the flexor tendon sheath. Full extension was regained by excising the tendon.
Hidehiko Saito, M.D., Tatsuya Tajima, M.D., Hideo Watanabe, M.D., and Hiroshi Yamamoto, M.D., Niigata, Japan
An epidermoid cyst is one of the common benign tumor-like conditions in the hand. Usually it is found in the palmar aspect of the fingers and the thumb and in the palm, being confined to the dermis and subcutaneous tissues. Epidermoid cysts in phalangeal bones, although rare, have been reported occasionally, but those arising in the tendon seem to be extremely rare. A review of the Japanese-language and English-language literatures disclosed only the report of Berkheiser. 1
Case report A 5-year-old girl was referred to our clinic with a small mass in the palm of her right hand and some limitation of
From the Department of Orthopedic Surgery. Niigata University. School of Medicine. Niigata. Japan. Received for publication Nov. 16. 1978. Reprint requests: Hidehiko Saito. M.D .• Department of Orthopedic Surgery. School of Medicine. Niigata University. Asahimachidori-I. Niigata. Japan.
extension of the middle finger. Her mother recalled that when the patient was 2 years of age she had complained of pain in the palm after playing. No open wound was found. and treatment was given for a sprain of the finger. There was no other specific history of trauma. The girl had been unable to extend the right middle finger fully for 2 years, and a mass in the palm of the right hand had been present for I year. On examination there was a dumbbell-shaped mass, I by 2 cm in size, in the palm along the flexors of the middle finger (Fig. I). This mass moved proximally and distally under the skin upon motion of the finger. Extension of the proximal interphalangeal joint was limited by 24°. At operation a yellow-brown mass was found in the tendon of the flexor superficialis. The lesion occupied almost the entire diameter of the tendon, distal gliding of which was blocked at the inlet of the flexor sheath. The tendon was divided proximal to the chiasma and at the wrist, and the segment containing the tumorous mass was removed. Full extension of the middle finger was regained. A longitudinal section of the mass showed a cyst filled with yellow-brown pasty material in the proximal portion and a firm nodule in the distal portion (Fig. 2).
Fig. 1. A dumbbell-shaped mass in the right palm moving under the skin on motion of the middle finger. 448
THE JOURNAL OF HAND SURGERY
0363-5023/79/040448+03$00.30/0 © 1979 American Society for Surgery of the Hand
Vol. 4, No.5 September, 1979
Epidermoid cyst of tendon
Fig. 2. A, The removed segment of the flexor superficiali s tendon of the middle finger occupied by a dumbell-shaped mass. B, The longitudinal section, showing a cyst filled with yellow-brown pasty material in the proximal portion of the mass.
Fig. 3. Photomicrograph showing the cyst wall to be composed of a well-developed keratinizing zone and squamous epithelium and a thin outer layer of fibrous connective tissue without skin appendages. (Original magnification: A, x8; B, x40.)
449
450
The Journal of HAND SURGERY
Saito et al.
Histological examination showed the cyst wall to be composed of a well-developed keratinizing zone and squamous epithelium and a thin outer layer of fibrous connective tissue which contained no skin appendages, such as hair follicles, sweat, or sebaceous glands (Fig. 3).
Discussion Among tumors and tumor-like conditions of the hand, the epidermoid cyst occurs relatively frequently, as demonstrated by Boyes,2 who reported 33 of 394 tumors of the hand to be epidermoid cysts (8.4%), and by Posch,3 who reported six of 147 to be epidermoid cysts (4.1 %). Neither report specifically mentioned tendon involvement. Epidermoid cysts in phalangeal bones, although rare, have been reported by several authors, including Carroll,4 Chakravorty and Coley,S and Byers, Mantle, and Salm.6 In 1955 Berkheiser l reported two cases of epithelial inclusion cyst involving a tendon; in one case the cyst was attached to the flexor sheath of the right little finger at the level of the distal phalanx, and in the other case to the flexor tendon at the level of the middle phalanx of the left index finger.
The widely accepted hypothesis is that trauma is the cause. Implantation of germinative epithelial cells into the deep tissue results from a perforating wound such as a stab wound, a laceration, a surgical incision, or even from a nonperforating wound, and forms a nidus from which an "epithelial pearl" grows. We assume that the cause of intratendinous epidermoid cysts also is explained by this same theory, although in this particular case, a history of specific trauma was not ascertained. REFERENCES I. Berkheiser SW: Epithelial inclusion cysts (epidermoid) of tendon. Guthrie Clin Bull 24: 147 -9, 1955 2. Boyes JH: Bunnell's surgery of the hand, ed 5. Philadelphia, 1970,18 Lippincott Co, p 666 3. Posch JL: Tumors of the hand. J Bone Joint Surg [Am]38:517-39, 1956. 4. Carroll RE: Epidermoid (epithelial) cyst of the hand skeleton. Am J Surg 85:327-34, 1953 5. Chakravorty RC, Coley BL: Epidermoid (epithelial) cyst of the phalanx. Am J Surg 87:917-20, 1954 6. Byers P, Mantle J, Salm R: Epidermal cysts of phalanges. J Bone Joint Surg [Br] 48:577-81, 1966
Hidehiko Saito, M.D., Tatsuya Tajima, M.D., Hideo Watanabe, M.D., and Hiroshi Yamamoto, M.D., Niigata, Japan
An epidermoid cyst is one of the common benign tumor-like conditions in the hand. Usually it is found in the palmar aspect of the fingers and the thumb and in the palm, being confined to the dermis and subcutaneous tissues. Epidermoid cysts in phalangeal bones, although rare, have been reported occasionally, but those arising in the tendon seem to be extremely rare. A review of the Japanese-language and English-language literatures disclosed only the report of Berkheiser. 1
Case report A 5-year-old girl was referred to our clinic with a small mass in the palm of her right hand and some limitation of
From the Department of Orthopedic Surgery. Niigata University. School of Medicine. Niigata. Japan. Received for publication Nov. 16. 1978. Reprint requests: Hidehiko Saito. M.D .• Department of Orthopedic Surgery. School of Medicine. Niigata University. Asahimachidori-I. Niigata. Japan.
extension of the middle finger. Her mother recalled that when the patient was 2 years of age she had complained of pain in the palm after playing. No open wound was found. and treatment was given for a sprain of the finger. There was no other specific history of trauma. The girl had been unable to extend the right middle finger fully for 2 years, and a mass in the palm of the right hand had been present for I year. On examination there was a dumbbell-shaped mass, I by 2 cm in size, in the palm along the flexors of the middle finger (Fig. I). This mass moved proximally and distally under the skin upon motion of the finger. Extension of the proximal interphalangeal joint was limited by 24°. At operation a yellow-brown mass was found in the tendon of the flexor superficialis. The lesion occupied almost the entire diameter of the tendon, distal gliding of which was blocked at the inlet of the flexor sheath. The tendon was divided proximal to the chiasma and at the wrist, and the segment containing the tumorous mass was removed. Full extension of the middle finger was regained. A longitudinal section of the mass showed a cyst filled with yellow-brown pasty material in the proximal portion and a firm nodule in the distal portion (Fig. 2).
Fig. 1. A dumbbell-shaped mass in the right palm moving under the skin on motion of the middle finger. 448
THE JOURNAL OF HAND SURGERY
0363-5023/79/040448+03$00.30/0 © 1979 American Society for Surgery of the Hand
Vol. 4, No.5 September, 1979
Epidermoid cyst of tendon
Fig. 2. A, The removed segment of the flexor superficiali s tendon of the middle finger occupied by a dumbell-shaped mass. B, The longitudinal section, showing a cyst filled with yellow-brown pasty material in the proximal portion of the mass.
Fig. 3. Photomicrograph showing the cyst wall to be composed of a well-developed keratinizing zone and squamous epithelium and a thin outer layer of fibrous connective tissue without skin appendages. (Original magnification: A, x8; B, x40.)
449
450
The Journal of HAND SURGERY
Saito et al.
Histological examination showed the cyst wall to be composed of a well-developed keratinizing zone and squamous epithelium and a thin outer layer of fibrous connective tissue which contained no skin appendages, such as hair follicles, sweat, or sebaceous glands (Fig. 3).
Discussion Among tumors and tumor-like conditions of the hand, the epidermoid cyst occurs relatively frequently, as demonstrated by Boyes,2 who reported 33 of 394 tumors of the hand to be epidermoid cysts (8.4%), and by Posch,3 who reported six of 147 to be epidermoid cysts (4.1 %). Neither report specifically mentioned tendon involvement. Epidermoid cysts in phalangeal bones, although rare, have been reported by several authors, including Carroll,4 Chakravorty and Coley,S and Byers, Mantle, and Salm.6 In 1955 Berkheiser l reported two cases of epithelial inclusion cyst involving a tendon; in one case the cyst was attached to the flexor sheath of the right little finger at the level of the distal phalanx, and in the other case to the flexor tendon at the level of the middle phalanx of the left index finger.
The widely accepted hypothesis is that trauma is the cause. Implantation of germinative epithelial cells into the deep tissue results from a perforating wound such as a stab wound, a laceration, a surgical incision, or even from a nonperforating wound, and forms a nidus from which an "epithelial pearl" grows. We assume that the cause of intratendinous epidermoid cysts also is explained by this same theory, although in this particular case, a history of specific trauma was not ascertained. REFERENCES I. Berkheiser SW: Epithelial inclusion cysts (epidermoid) of tendon. Guthrie Clin Bull 24: 147 -9, 1955 2. Boyes JH: Bunnell's surgery of the hand, ed 5. Philadelphia, 1970,18 Lippincott Co, p 666 3. Posch JL: Tumors of the hand. J Bone Joint Surg [Am]38:517-39, 1956. 4. Carroll RE: Epidermoid (epithelial) cyst of the hand skeleton. Am J Surg 85:327-34, 1953 5. Chakravorty RC, Coley BL: Epidermoid (epithelial) cyst of the phalanx. Am J Surg 87:917-20, 1954 6. Byers P, Mantle J, Salm R: Epidermal cysts of phalanges. J Bone Joint Surg [Br] 48:577-81, 1966