The clinical decision on when to biopsy a skin lesion to exclude skin cancer - the BLINCK approach
It is well known that early detection of skin cancer generally equates to improved outcome. In Australia, where the incidence of skin cancer is higher than any other country in the world, and where there are currently less than 400 dermatologists available to monitor a population of 24 million, it is essential that primary care “family” doctors are trained to recognise the early features of skin cancer. The decision to excise or biopsy a suspicious skin lesion is often problematic for these generalist primary care doctors who frequently have not had access to skin cancer training. On one hand, the family doctor does not want to miss detecting a potentially fatal skin cancer but on the other does not want to excise an excessive number of benign lesions. As well, with improved public awareness of skin cancer in Australia in recent years, more than ever patients are requesting their family doctors to do skin examinations to exclude skin cancer.
Dermoscopy has been shown to be a significant aid in the diagnosis of melanoma and non-melanoma skin cancer. However, for some skin cancers, such as melanoma in situ, hypo/amelanotic melanoma, naevoid melanoma and Merkel cell carcinoma, recognition by purely dermoscopic appearance is sometimes very difficult, even for experienced dermoscopists. The author feels that perhaps broader consideration of other clues within the history and examination of patients with skin lesions has been overshadowed in recent times by the pursuit of dermatoscopic excellence.
Ultimately, the clinician must make the decision whether to biopsy a skin lesion or not. It is impractical to hope that all primary care doctors in Australia will become expert dermoscopists, and hence the author would like to present an approach based on his own clinical experience, that may assist family doctors with this decision making process. This method has not been scientifically trialed, but has assisted the author in detecting in situ melanomas in his own practice, as well as several less common skin cancers which may have been missed if only their dermoscopy appearance were assessed.
The acronym, “BLINCK”, refers to a logical progression of clinical questions that should be asked when examining a suspicious skin lesion. The author, a primary care doctor with a special interest in dermoscopy, has found this approach to be helpful in the detection of “difficult to diagnose” skin cancers that may have been missed solely by dermoscopic appraisal. This approach requires that the user have at least a fundamental knowledge of dermoscopy and be aware of the classical dermatoscopic criteria for malignancy.
B – Benign
o Is the lesion immediately recognisable as a common benign tumour, on clinical and dermatoscopic examination, with other similar lesions being present on that part of the body e.g. typical solar lentigo, seborrheic keratosis, haemangioma, dermatofibroma?
If the answer is ‘yes’, no further action is required.
If the answer is ‘no’, then proceed to the following:
L –Lonely
o Is this lesion, clinically and dermatoscopically, the only one of its type on that region of the body, i.e. an “ugly duckling”?
‘Yes’ scores 1
I –Irregular
o Is this lesion dermatoscopically irregular, that is, does it have an asymmetrical pigmentation pattern and
more than one colour, (after Menzies)?
‘Yes’ scores 1
N –Nervous
o Is the patient nervous that the lesion may be a skin cancer despite an assurance by the clinician that this is unlikely?
C –Change
o Does the patient give a subjective history of the lesion changing?
Only a total score of 1 can be given if either or both
of these last two questions are answered ‘yes’
K –Known clues
o Does the lesion have any definite known dermatoscopic clues to malignancy? (Any of the standard dermatoscopic criteria for malignancy may be used)
‘Yes’ scores 1
If the lesion scores 2 or more out of 4, then it should be biopsied
If there is a score of 1 or 0, the lesion does not require biopsy and may be either reviewed at a later time, digitally monitored, or the patient simply reassured that the lesion is benign. This will depend upon the clinical scenario.
In recent years, this approach has greatly assisted the author in diagnosing melanomas in his own practice, many of which have appeared to have no classical dermatoscopic features of malignancy.
Patient concern for a lesion, (“Nervous”), has been included for two reasons. Firstly, lesions that appear at first glance to be completely innocent are sometimes given only a cursory inspection by the examining doctor during a skin examination. The patient, however, may have additional information regarding this lesion that they do not divulge to the doctor, such as a history of bleeding, itching or change. Hence, a patient’s concern over a lesion may represent more than just, so-called, “sixth sense”.
Secondly, there may be a medico-legal aspect to “patient concern”. In the unfortunate circumstance of a lesion being initially dismissed by the clinician as being benign, and then subsequently being excised and shown to be melanoma, the patient may prove to be less forgiving if they specifically expressed concern over this lesion at the initial presentation.
The two questions labeled “Nervous” and “Change” have been grouped together in an attempt to maximise the specificity of this method. One point is scored if either is present, but still only 1 point is scored if both are present. This is because one of the common causes of patient concern for a lesion is in fact a subjective history of change. If two points were allocated in this situation, despite there being no other positive features, then all such lesions would require excision. In the author’s opinion, this would result in too many benign lesions being removed.
With regards the situation where a skin lesion is assessed as showing one or more definite dermatoscopic features of malignancy, yet the lesion is judged to have a symmetrical pigmentation pattern, one colour, no “ugly duckling” features and no history of change, then the BLINCK approach would lead the clinician to not biopsy this lesion, (score of 1). The author feels that this is still the correct course of action as it is more likely that the assessed “criteria” for malignancy represents a false positive appraisal, rather than the lesion actually being a skin cancer.
Below are three examples from the author’s practice. In each case, the patient presented for a routine skin examination and was not aware of the lesion in question.
Case 1: On full skin examination, this 66 year old male appeared to have only one naevus on his back. All other pigmented lesions in this area were solar lentigines or small seborrheic keratoses. This presumed naevus was soft and demonstrated the “wobble sign”. The dermoscopy appearance was reasonably bland but it was judged that there was an asymmetrical pigmentation pattern and more than one colour present. There were possibly some minor vague grey areas suggestive of regression but this feature was so subtle that it was not considered significant enough to be included in the assessment. Hence, it was felt that there were no definite known criteria for melanoma seen.
Using the BLINCK method, the lesion was assessed as not being classically benign, (B), as there were no other similar lesions present on that part of the body. The next five questions were considered and it was felt that the lesion was an “ugly duckling”, (L) and dermatoscopically irregular (I). The patient was not nervous about this lesion being a cancer, (N), and there was no history of change, (C). This resulted in a score of 2 and the lesion was excised.
Histology revealed a Clark’s level 2, 0.3mm superficial spreading melanoma overlying an intradermal naevus, with focal regression. Based on the soft, fleshy clinical appearance of the lesion and the bland dermatoscopic impression, the author feels that many clinicians may not have chosen to biopsy this lesion until it had become more invasive and easily recognisable. The fact that the lesion was an “ugly duckling”, despite being soft and only slightly irregular dermatoscopically, fortunately prompted immediate biopsy.
Case 1: Clinical view
Case 1 Dermatoscopic view
Case 2: A 41 year old woman was noticed to have a light brown macular lesion on the left upper arm, which was noticeably larger than any other lesion on this limb. She had multiple solar lentigines on the back but none appeared to be as large as this lesion. Hence, it was unable to be classed as definitely “benign”, (B), as per the above definition. Even though it was an “ugly duckling”, (L), the dermoscopic appearance was again remarkably bland. However, it was felt that the pigmentation pattern was irregular and that there were 2 colours, tan and dark brown, (I). There was no patient concern, (N), no history of change, (C), and no obvious dermoscopic features of malignancy, (K). This resulted in a score of 2 and the lesion was excised.
Histology revealed a melanoma in situ arising in a lentiginous junctional dysplastic naevus. The author feels that the dermoscopic appearance of this lesion alone may not have been sufficient to lead to a diagnosis of melanoma and that the inclusion of other clinical aspects was helpful in deciding upon the correct course of action.
Case 2: Clinical view
Case 2 Dermatoscopic view
Case 3: An 80 year old woman presented for a routine skin check. An irregular, pigmented, macular lesion was noted on the right jaw area that was larger than her surrounding solar lentigines. This lesion was considered to be an “ugly duckling”, (L), as well as having an irregular pigmentation pattern and two colours, (I). The patient was not aware of the lesion, (N,C), and the author was unable to confidently describe any known dermoscopy features of malignancy, (K). As this lesion scored 2, it was excised and a diagnosis of in situ lentigo maligna melanoma with regression was made on histology.
Case 3: Clinical view
Case 3 Dermoscopy
In summary, the BLINCK approach is presented as a simple method to assist the clinician with the decision whether to biopsy a skin lesion or not. It is hoped that the use of this method will improve the pickup rate of potentially fatal skin cancers as well as reduce the number of unnecessary benign lesion excisions. This approach may be especially helpful to clinicians who have only a basic or intermediate level of dermoscopy skills but who are regularly called upon to assess skin lesions in their practices.
Peter Bourne
