› Forums › General Melanoma Community › Clark’s level versus Breslow depth?
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Janner.
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- December 17, 2014 at 4:31 pm
Can anyone help me understand the difference between Clark's level and Breslow depth? Aren't they basically measuring the same thing, i.e. depth or thickness of lesion? Is the significance of Clark's level based on the thickness of the layers of skin in different areas of the body? I have read that Clark's level is not really a good prognostic indicator but Breslow depth is, but if they are measuring the same thing, the thickness of the melanoma and how deeply it penetrates the skin layers, how can one be helpful and the other not?
Insight?
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- December 17, 2014 at 5:19 pm
most discount the Clarks Level as predictive of outcome and rely primarily on the Breslow level and mitotic value
research over many years has shown that the predictive value of the depth is far stronger than that of the Clark level. Many labs no longer routinely report Clark level.
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- December 17, 2014 at 5:19 pm
most discount the Clarks Level as predictive of outcome and rely primarily on the Breslow level and mitotic value
research over many years has shown that the predictive value of the depth is far stronger than that of the Clark level. Many labs no longer routinely report Clark level.
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- December 17, 2014 at 5:19 pm
most discount the Clarks Level as predictive of outcome and rely primarily on the Breslow level and mitotic value
research over many years has shown that the predictive value of the depth is far stronger than that of the Clark level. Many labs no longer routinely report Clark level.
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- December 17, 2014 at 6:54 pm
Clark's Level is subjective. It isn't a distinct "feature" in the skin but a subjective opinion. Breslow depth is an exact measurement. Different pathologists look at the same skin sample and come up with a different Clark's Level. So it's easier to get statistical significance on an exact measurement of depth than a subjective version of skin level.
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- December 18, 2014 at 4:02 am
Thank you for the responses. Are the levels not well defined under a microscope?
Does the thickness of the different layers vary between individuals?
I guess I just can't understand how someone could have a melanoma that measures 1.3 mm on their back that is Clark level IV, and another person has a melanoma that is 1.3 mm on their back but is Clark level II. Wouldn't all 1.3 mm melanomas on the back by definition be the same depth and reach the same layer of skin?
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- December 18, 2014 at 6:50 am
Skin thickness varies on different parts of the anatomy. But read the description of the skin "levels" below and you can see where "subjective" comes into play. Level 2, 3, and 4 are open to interpretation. 1 and 5 have much more defined boundaries.
Clark's Level (NCCN website) Another system describes the thickness of a melanoma in relation to its penetration into the skin instead of actually measuring it. The Clark level of a melanoma uses a scale of I to V to describe thickness (with higher numbers indicating a deeper melanoma): (The Clark level Roman numerals should not be confused with the stage grouping Roman numerals.)
- if the melanoma stays in the epidermis (Clark level I)
- if the melanoma has begun to penetrate to the upper dermis (Clark level II)
- if the melanoma involves most of the upper dermis (Clark level III)
- if the melanoma has penetrated to the lower dermis (Clark level IV)
- if the melanoma has penetrated very deeply, to the subcutis (Clark level V)
In the newest classification, the Breslow measurement of thickness has become more important than the Clark level of penetration as the first prognostic factor. This is because the thickness measurement is easier and depends less on the pathologist’s judgment. Sometimes, however, the Clark level tells us that a melanoma is more advanced than we may think it is from the Breslow measurement. Therefore, both systems are often used to help stage a melanoma. In either system, the melanoma has a worse prognosis if the pathologist says it is ulcerated (covering layer of epidermis is absent). -
- December 18, 2014 at 6:50 am
Skin thickness varies on different parts of the anatomy. But read the description of the skin "levels" below and you can see where "subjective" comes into play. Level 2, 3, and 4 are open to interpretation. 1 and 5 have much more defined boundaries.
Clark's Level (NCCN website) Another system describes the thickness of a melanoma in relation to its penetration into the skin instead of actually measuring it. The Clark level of a melanoma uses a scale of I to V to describe thickness (with higher numbers indicating a deeper melanoma): (The Clark level Roman numerals should not be confused with the stage grouping Roman numerals.)
- if the melanoma stays in the epidermis (Clark level I)
- if the melanoma has begun to penetrate to the upper dermis (Clark level II)
- if the melanoma involves most of the upper dermis (Clark level III)
- if the melanoma has penetrated to the lower dermis (Clark level IV)
- if the melanoma has penetrated very deeply, to the subcutis (Clark level V)
In the newest classification, the Breslow measurement of thickness has become more important than the Clark level of penetration as the first prognostic factor. This is because the thickness measurement is easier and depends less on the pathologist’s judgment. Sometimes, however, the Clark level tells us that a melanoma is more advanced than we may think it is from the Breslow measurement. Therefore, both systems are often used to help stage a melanoma. In either system, the melanoma has a worse prognosis if the pathologist says it is ulcerated (covering layer of epidermis is absent). -
- December 18, 2014 at 6:50 am
Skin thickness varies on different parts of the anatomy. But read the description of the skin "levels" below and you can see where "subjective" comes into play. Level 2, 3, and 4 are open to interpretation. 1 and 5 have much more defined boundaries.
Clark's Level (NCCN website) Another system describes the thickness of a melanoma in relation to its penetration into the skin instead of actually measuring it. The Clark level of a melanoma uses a scale of I to V to describe thickness (with higher numbers indicating a deeper melanoma): (The Clark level Roman numerals should not be confused with the stage grouping Roman numerals.)
- if the melanoma stays in the epidermis (Clark level I)
- if the melanoma has begun to penetrate to the upper dermis (Clark level II)
- if the melanoma involves most of the upper dermis (Clark level III)
- if the melanoma has penetrated to the lower dermis (Clark level IV)
- if the melanoma has penetrated very deeply, to the subcutis (Clark level V)
In the newest classification, the Breslow measurement of thickness has become more important than the Clark level of penetration as the first prognostic factor. This is because the thickness measurement is easier and depends less on the pathologist’s judgment. Sometimes, however, the Clark level tells us that a melanoma is more advanced than we may think it is from the Breslow measurement. Therefore, both systems are often used to help stage a melanoma. In either system, the melanoma has a worse prognosis if the pathologist says it is ulcerated (covering layer of epidermis is absent). -
- December 18, 2014 at 4:13 pm
Thank you. So, if I understand right, it would be useful if it told us that a thin melanoma has actually reached the lymphovascular part of the dermis, but otherwise it is fairly subjective, whereas Breslow level is a measurement in millimeters that would have very little variation from one pathologist to another. So each Clark level is not of uniform thickness and might vary from place to place and person to person. And a thin melanoma might in fact have reached a lower level of the dermis if the skin was thinner in that area.
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- December 18, 2014 at 4:13 pm
Thank you. So, if I understand right, it would be useful if it told us that a thin melanoma has actually reached the lymphovascular part of the dermis, but otherwise it is fairly subjective, whereas Breslow level is a measurement in millimeters that would have very little variation from one pathologist to another. So each Clark level is not of uniform thickness and might vary from place to place and person to person. And a thin melanoma might in fact have reached a lower level of the dermis if the skin was thinner in that area.
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- December 19, 2014 at 1:46 am
Exactly. That's why previous staging (prior to 2010) used Clark's Level IV as a negative factor moving a person from stage IA to IB. Staging is different now and Clark's Level isn't used – but a thin melanoma with Clark Level IV was considered higher risk than a medium depth melanoma that was maybe Clark Level II-III. Skin levels (papillary dermis to reticular) are not uniform. Look at this stained skin sample to see — even in this one slide – how the location of the skin layers is variable.
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- December 19, 2014 at 1:46 am
Exactly. That's why previous staging (prior to 2010) used Clark's Level IV as a negative factor moving a person from stage IA to IB. Staging is different now and Clark's Level isn't used – but a thin melanoma with Clark Level IV was considered higher risk than a medium depth melanoma that was maybe Clark Level II-III. Skin levels (papillary dermis to reticular) are not uniform. Look at this stained skin sample to see — even in this one slide – how the location of the skin layers is variable.
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- December 19, 2014 at 1:46 am
Exactly. That's why previous staging (prior to 2010) used Clark's Level IV as a negative factor moving a person from stage IA to IB. Staging is different now and Clark's Level isn't used – but a thin melanoma with Clark Level IV was considered higher risk than a medium depth melanoma that was maybe Clark Level II-III. Skin levels (papillary dermis to reticular) are not uniform. Look at this stained skin sample to see — even in this one slide – how the location of the skin layers is variable.
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- December 18, 2014 at 4:13 pm
Thank you. So, if I understand right, it would be useful if it told us that a thin melanoma has actually reached the lymphovascular part of the dermis, but otherwise it is fairly subjective, whereas Breslow level is a measurement in millimeters that would have very little variation from one pathologist to another. So each Clark level is not of uniform thickness and might vary from place to place and person to person. And a thin melanoma might in fact have reached a lower level of the dermis if the skin was thinner in that area.
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- December 18, 2014 at 6:54 am
Btw, a depth of 1.3mm would most likely be level 4 on most people. Rarely 3 but unlikely to be level 2. It's really more telling if you have a very thin melanoma – say .4mm and that is level 4. The lower in the skin structures you go, the closer you get to blood and lymph vessels, and these are what transport melanoma elsewhere.
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- December 18, 2014 at 6:54 am
Btw, a depth of 1.3mm would most likely be level 4 on most people. Rarely 3 but unlikely to be level 2. It's really more telling if you have a very thin melanoma – say .4mm and that is level 4. The lower in the skin structures you go, the closer you get to blood and lymph vessels, and these are what transport melanoma elsewhere.
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- December 18, 2014 at 6:54 am
Btw, a depth of 1.3mm would most likely be level 4 on most people. Rarely 3 but unlikely to be level 2. It's really more telling if you have a very thin melanoma – say .4mm and that is level 4. The lower in the skin structures you go, the closer you get to blood and lymph vessels, and these are what transport melanoma elsewhere.
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- December 18, 2014 at 4:02 am
Thank you for the responses. Are the levels not well defined under a microscope?
Does the thickness of the different layers vary between individuals?
I guess I just can't understand how someone could have a melanoma that measures 1.3 mm on their back that is Clark level IV, and another person has a melanoma that is 1.3 mm on their back but is Clark level II. Wouldn't all 1.3 mm melanomas on the back by definition be the same depth and reach the same layer of skin?
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- December 18, 2014 at 4:02 am
Thank you for the responses. Are the levels not well defined under a microscope?
Does the thickness of the different layers vary between individuals?
I guess I just can't understand how someone could have a melanoma that measures 1.3 mm on their back that is Clark level IV, and another person has a melanoma that is 1.3 mm on their back but is Clark level II. Wouldn't all 1.3 mm melanomas on the back by definition be the same depth and reach the same layer of skin?
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- December 17, 2014 at 6:54 pm
Clark's Level is subjective. It isn't a distinct "feature" in the skin but a subjective opinion. Breslow depth is an exact measurement. Different pathologists look at the same skin sample and come up with a different Clark's Level. So it's easier to get statistical significance on an exact measurement of depth than a subjective version of skin level.
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- December 17, 2014 at 6:54 pm
Clark's Level is subjective. It isn't a distinct "feature" in the skin but a subjective opinion. Breslow depth is an exact measurement. Different pathologists look at the same skin sample and come up with a different Clark's Level. So it's easier to get statistical significance on an exact measurement of depth than a subjective version of skin level.
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