Symposium Anorectal Problems: Etiology of Pilonidal
Sinus
PETER H. LORD, M.CHIR., F.R.C.S.* London, England
D R . FERGUSON
Now I will call on Mr. Peter Lord of Beaconsfield, England, for a discussion of the etiology of pilonidal sinus. MR.
M./
LORD
Pilonidal sinus has long been a source of controversy, some of it quite heated, and a lack of understanding of the etiology has led to many forms of treatment, some more successful than others. This paper, which is based on clinical observation, is an attempt to clarify this problem of etiology. T h e r e are certain aspects of the condition which we all accept but which have to be explained by any theory of etiology, for example, pitonidat sinus is a condition of young people and its onset is normally 6 to 16 years after puberty. On inspection we always find pits in the midline. It can be seen macroscopically that the skin grows down to line these midline pits, and this observation is confirmed on microscopic section. Deep to the midline pits there may or may not be hair. If a pilonidal sinus becomes infected and discharges we then get a new opening, quite different from the original midline pits. Whereas the pits have an obviously congenital appearance, this new opening is quite definitely acquired. It is raised and pink, and on section it can be seen that at
/
FIG. 1. Curl of h a i r r e m o v e d from the pilonidal sinus of a 19-year-old y o u t h . It consists of 23 hairs identical to each o t h e r in length, diameter, color a n d orientation.
the surface the skin gives way to granulation tissue which lines the tract r u n n i n g towards this new opening from the area deep to the midline pits. T h e r e is an interesting and constant relationship between the lateral sinus opening and the midline pits. T h e opening is always cephalad in relation to the pits. T h i s interesting observation is referred to again below. T h e statements so far made are in no way controversial. T h e y are all easily confirmed by the macroscopic and microscopic examination of a few pilonidal sinuses. T h e controversy in pilonidal sinus concerns the source of the hair which is usually present and which lies deep to the midline pits. H a i r can only come from hair follicles, and there are either no hair follicles or very few indeed in a pilonidal sinus.
*10 Harley Street, L o n d o n W.I, England.
661 Dis. Col. & Rect. Nov.-Dec. 1975
Volume 18 Number 8
662
LORD
Because of the lack of hair follicles, m a n y ingenious theories have been put forward to explain how hair can enter a pilonidal sinus from outside. Some of these theories are based more on speculation than observation. T h e attthor believes that the answer to this problem has come from contemplation 9 of Figure 1. This is a curl of hair removed from the pilonidal sinus of a 19-year-old youth. This curl consists of 23 hairs, identical each to the other in length, diameter, color and orientation. It is hard to conceive that any of the theories that explain how hair can get into a pilonidal sinus from outside could possibly explain how 23 hairs should follow each other into a pilonidal sinus and each hair be identical in every respect to the last. Here we must digress for a moment to say that there are several forms of hair follicles in the h u m a n body; for example, there are head hair follicles which begin to function before birth and which when mature produce a hair that grows to a length of about 2 feet before it is shed. T h e r e are pubic hair follicles, which begin to function at puberty and which grow a hair that is shed when it is approximately I ~ inches long. We would all look very different if these follicles became confused. If we now look at our picture I am sure we would all agree that this is a curl of pubic hairs, and it seems reasonable tO postulate that in the depths of the pilonidal sinus, related in some way to the congenital midline pits, there was a hair follicle of the pubic-hair type, which began to function at puberty and which grew a hair approximately 1 89 inches long into the tissues deep to the midline pits. This hair was then shed, and the same follicle began to grow another one identical in every respect to the first. This process would be repeated every three to six months, and by the time the patient was t9 years of age there were 23 hairs alongside each other, all coming from the same hair follicle; at this moment, the
Dis. Col. & P, ect. Nov.-Dee. 1975
lesion became infected and the patient became aware of it for the first time. T h e infection may well have destroyed that solitary hair follicle, but even if it were still present, it would be very difficult to find it and to demonstrate it unequivocally on histologic section. T h e next observation of interest is the direction of growth of the pubic-type hairs in tile natal cleft. T h e y never grow towards the anus, but normally grow towards the midline and away from the anus, i.e., cephalad. This fits in well with the observation that the lateral sinus opening is normally cephalad in relation to the midline pits, and is in keeping with the suggestion that the cur! of hair in a pilonidal sinus comes from a solitary follicle of the pubic-hair type which is in fact oriented in the same direction as the other pubic hair follicles in that part of the anatomy. If this hypothesis is acceptable the treatment of pilonidal sinus becomes very simple. We must remove the midline pits and with them the offending hair follicle, remove all the hairs that have already been shed into the lesion, and allow it to heal, on the grounds that all sinuses and fistulas heal unless there is something keeping them open. It is my practice to carry out this procedure using local anesthesia. T h e pits are removed through a small elliptical incision, removing with the pits a narrow strip of skin about .5 cm wide and not more than 2 cm long. Any tracts are cleaned out to remove all hair using a small electric razor cleaning brush. T h e brush is pushed down the tract, rotated and withdrawn. Any hairs will be caught up in the bristles. T h e process is repeated until the brush is returned free of hairs. Sinus forceps are also pushed down the tract to make sure that there is no loculation, and finally the external lateral sinus opening is excised. T h e end result is as illustrated in Figure 2. This, of course, is a very simple pilonidal sinus, but the same
Volume 18 Number 8
FIG. 2. Simple pilonidal sinus. T h e midline pits have been removed using local anesthesia. T h e opening of the lateral tract is clearly visible.
Fze. 3. Complicated pilonidal sinus. This patient had had symptoms for many years. T h e r e were three groups of midline pits and three lateral tracts. Healing was obtained without further surgery.
FIG. 4. An acquired pilonidal sinus caused by hair growing into the site of a previous excision.
SYMPOSIUM--PILONIDAL SINUS
663
664
Logo
j
t
.
j J
~---'--'-'---
~'u~
(EPH~L~D
Fro. 5. Diagrammatic representation of ditions that lead to acquired pilonidal sinus.
con-
method is equally well applied to the most complex sinus, such as that in Figure 3. Many surgeons will feel that such a simple form of treatment is unlikely to succeed when complicated methods are known to have a failure rate. It has perhaps been assumed that when a patient has a recurrent lesion following excision of pilonidal sinus, i.e., failure of treatment, the new lesion is similar in every respect to the original one; but careful inspection reveals that this is not so. T h e hair in the new acquired pilonidal sinus is rooted in the skin near the site of excision, and as the hairs in this region grow towards the mid-
Dis, Col. & Reet. Nov.-Dec. 197.5
line and cephalad, these rooted hairs have a tendency to grow so that their tips bend over into tile operative wound. Just one hair growing in this way over the edge of the excision wound will prevent healing, as there is no force in the healing process capable of pushing out the hair, which is fixed and rooted in the skin around the edge. If another hair in that area manages to get in it also will not come out, and before long we have a condition where there are a n u m b e r of hairs, all rooted on the outside but growing into the midline wound and forming a tract. Figure 4 illustrates just such a lesion, with all those hairs growing down into a midline opening. I feel that a mistake in the past has been to call this lesion a recurrent pilonidal sinus, suggesting thereby that it is similar in nature to the original condition, and that perhaps a more radical treatment is needed. I would like to suggest that we call this an "acquired pilonidal sinus" to distinguish it from the original lesion. In order to avoid this complication, or in order to cure it if it happens, we have to shave around the area of the incision for a hair's length. It is vital that this shaving be continued until complete and firm healing has taken place, usually three or four weeks. T h e edge of the wound is kept meticulously shaved so that not a single hair is able to grow over the edge and into the wound. One hair left in position will be enough to prevent the lesion from healing.
Sinus
PETER H. LORD, M.CHIR., F.R.C.S.* London, England
D R . FERGUSON
Now I will call on Mr. Peter Lord of Beaconsfield, England, for a discussion of the etiology of pilonidal sinus. MR.
M./
LORD
Pilonidal sinus has long been a source of controversy, some of it quite heated, and a lack of understanding of the etiology has led to many forms of treatment, some more successful than others. This paper, which is based on clinical observation, is an attempt to clarify this problem of etiology. T h e r e are certain aspects of the condition which we all accept but which have to be explained by any theory of etiology, for example, pitonidat sinus is a condition of young people and its onset is normally 6 to 16 years after puberty. On inspection we always find pits in the midline. It can be seen macroscopically that the skin grows down to line these midline pits, and this observation is confirmed on microscopic section. Deep to the midline pits there may or may not be hair. If a pilonidal sinus becomes infected and discharges we then get a new opening, quite different from the original midline pits. Whereas the pits have an obviously congenital appearance, this new opening is quite definitely acquired. It is raised and pink, and on section it can be seen that at
/
FIG. 1. Curl of h a i r r e m o v e d from the pilonidal sinus of a 19-year-old y o u t h . It consists of 23 hairs identical to each o t h e r in length, diameter, color a n d orientation.
the surface the skin gives way to granulation tissue which lines the tract r u n n i n g towards this new opening from the area deep to the midline pits. T h e r e is an interesting and constant relationship between the lateral sinus opening and the midline pits. T h e opening is always cephalad in relation to the pits. T h i s interesting observation is referred to again below. T h e statements so far made are in no way controversial. T h e y are all easily confirmed by the macroscopic and microscopic examination of a few pilonidal sinuses. T h e controversy in pilonidal sinus concerns the source of the hair which is usually present and which lies deep to the midline pits. H a i r can only come from hair follicles, and there are either no hair follicles or very few indeed in a pilonidal sinus.
*10 Harley Street, L o n d o n W.I, England.
661 Dis. Col. & Rect. Nov.-Dec. 1975
Volume 18 Number 8
662
LORD
Because of the lack of hair follicles, m a n y ingenious theories have been put forward to explain how hair can enter a pilonidal sinus from outside. Some of these theories are based more on speculation than observation. T h e attthor believes that the answer to this problem has come from contemplation 9 of Figure 1. This is a curl of hair removed from the pilonidal sinus of a 19-year-old youth. This curl consists of 23 hairs, identical each to the other in length, diameter, color and orientation. It is hard to conceive that any of the theories that explain how hair can get into a pilonidal sinus from outside could possibly explain how 23 hairs should follow each other into a pilonidal sinus and each hair be identical in every respect to the last. Here we must digress for a moment to say that there are several forms of hair follicles in the h u m a n body; for example, there are head hair follicles which begin to function before birth and which when mature produce a hair that grows to a length of about 2 feet before it is shed. T h e r e are pubic hair follicles, which begin to function at puberty and which grow a hair that is shed when it is approximately I ~ inches long. We would all look very different if these follicles became confused. If we now look at our picture I am sure we would all agree that this is a curl of pubic hairs, and it seems reasonable tO postulate that in the depths of the pilonidal sinus, related in some way to the congenital midline pits, there was a hair follicle of the pubic-hair type, which began to function at puberty and which grew a hair approximately 1 89 inches long into the tissues deep to the midline pits. This hair was then shed, and the same follicle began to grow another one identical in every respect to the first. This process would be repeated every three to six months, and by the time the patient was t9 years of age there were 23 hairs alongside each other, all coming from the same hair follicle; at this moment, the
Dis. Col. & P, ect. Nov.-Dee. 1975
lesion became infected and the patient became aware of it for the first time. T h e infection may well have destroyed that solitary hair follicle, but even if it were still present, it would be very difficult to find it and to demonstrate it unequivocally on histologic section. T h e next observation of interest is the direction of growth of the pubic-type hairs in tile natal cleft. T h e y never grow towards the anus, but normally grow towards the midline and away from the anus, i.e., cephalad. This fits in well with the observation that the lateral sinus opening is normally cephalad in relation to the midline pits, and is in keeping with the suggestion that the cur! of hair in a pilonidal sinus comes from a solitary follicle of the pubic-hair type which is in fact oriented in the same direction as the other pubic hair follicles in that part of the anatomy. If this hypothesis is acceptable the treatment of pilonidal sinus becomes very simple. We must remove the midline pits and with them the offending hair follicle, remove all the hairs that have already been shed into the lesion, and allow it to heal, on the grounds that all sinuses and fistulas heal unless there is something keeping them open. It is my practice to carry out this procedure using local anesthesia. T h e pits are removed through a small elliptical incision, removing with the pits a narrow strip of skin about .5 cm wide and not more than 2 cm long. Any tracts are cleaned out to remove all hair using a small electric razor cleaning brush. T h e brush is pushed down the tract, rotated and withdrawn. Any hairs will be caught up in the bristles. T h e process is repeated until the brush is returned free of hairs. Sinus forceps are also pushed down the tract to make sure that there is no loculation, and finally the external lateral sinus opening is excised. T h e end result is as illustrated in Figure 2. This, of course, is a very simple pilonidal sinus, but the same
Volume 18 Number 8
FIG. 2. Simple pilonidal sinus. T h e midline pits have been removed using local anesthesia. T h e opening of the lateral tract is clearly visible.
Fze. 3. Complicated pilonidal sinus. This patient had had symptoms for many years. T h e r e were three groups of midline pits and three lateral tracts. Healing was obtained without further surgery.
FIG. 4. An acquired pilonidal sinus caused by hair growing into the site of a previous excision.
SYMPOSIUM--PILONIDAL SINUS
663
664
Logo
j
t
.
j J
~---'--'-'---
~'u~
(EPH~L~D
Fro. 5. Diagrammatic representation of ditions that lead to acquired pilonidal sinus.
con-
method is equally well applied to the most complex sinus, such as that in Figure 3. Many surgeons will feel that such a simple form of treatment is unlikely to succeed when complicated methods are known to have a failure rate. It has perhaps been assumed that when a patient has a recurrent lesion following excision of pilonidal sinus, i.e., failure of treatment, the new lesion is similar in every respect to the original one; but careful inspection reveals that this is not so. T h e hair in the new acquired pilonidal sinus is rooted in the skin near the site of excision, and as the hairs in this region grow towards the mid-
Dis, Col. & Reet. Nov.-Dec. 197.5
line and cephalad, these rooted hairs have a tendency to grow so that their tips bend over into tile operative wound. Just one hair growing in this way over the edge of the excision wound will prevent healing, as there is no force in the healing process capable of pushing out the hair, which is fixed and rooted in the skin around the edge. If another hair in that area manages to get in it also will not come out, and before long we have a condition where there are a n u m b e r of hairs, all rooted on the outside but growing into the midline wound and forming a tract. Figure 4 illustrates just such a lesion, with all those hairs growing down into a midline opening. I feel that a mistake in the past has been to call this lesion a recurrent pilonidal sinus, suggesting thereby that it is similar in nature to the original condition, and that perhaps a more radical treatment is needed. I would like to suggest that we call this an "acquired pilonidal sinus" to distinguish it from the original lesion. In order to avoid this complication, or in order to cure it if it happens, we have to shave around the area of the incision for a hair's length. It is vital that this shaving be continued until complete and firm healing has taken place, usually three or four weeks. T h e edge of the wound is kept meticulously shaved so that not a single hair is able to grow over the edge and into the wound. One hair left in position will be enough to prevent the lesion from healing.
