These are questions and ideas I thought of myself. If shearing forces can affect the parallel furrow pattern why can’t similar forces affect other structures besides those seen in a melanocytic lesion? For example in a basil cell carcinoma why can’t shearing forces cause an arborizing vessel appearance to instead appear as polymorphous or dotted? Or why can’t the blue-white veil overlying raised area instead appear homogenous? Or why can’t a typical network appear atypical? Or why can’t a regular globular pattern appear irregular?
Why is a lattice pattern instead of a parallel furrow pattern present on the arch which clinically without a biomechanical analysis would appear non weightbearing? One cannot just look at the arch and assume it is non weight bearing.
The answer to this puzzle is that the biomechanical exam yields information unknown to only a dermatoscopic exam. There are different biomechanical faults in different planes be it your sagittal, transverse and frontal planes. Some of these faults occur on the rearfoot, some on the forefoot while some are uncompensated, partially compensated and fully compensated.
Key: After a complete biomechanical evaluation and fully checking the shoe gear and insoles, if there is a biomechanical deformity (with or without any degree of compensation) which results in biomechanical non weight bearing area with very limited shearing forces, plus a dermatoscopic exam with a fibrillar pattern then one must biopsy.
I thought of combining a gait analysis and static exam including shoe gear analysis and how such forces affect one’s dermatoscopic images. This topic is further discussed in the post below.
FOOT DERMOSCOPY- This video was not rehearsed. It was an impromptu recording made with me holding a cell phone camera. My goal was to clarify the relationship between biomechanical faults affecting melanocytic lesions on the plantar skin of the feet. I reviewed an axis of motion located on the transverse and frontal planes and clarified that the most motion occurs on the sagittal plane. I followed by emphasizing the sagittal plane compensation of a flexible plantarflexed first ray generally not resulting in a melanocytic lesion with a fibrillar pattern. The point is that anatomic location on the weight bearing portions of the foot alone is not the only factor in determining if a melanocytic lesion is a fibrillar pattern. Biomechanical faults too must be evaluated.
This is why dermoscopy and biomechanical exams must be tied together in the presence of melanocytic lesions on the plantar skin of the foot.
The plantar skin of the foot is your dermatoglyphic areas with ridges and furrows. I believe a better name for the furrows is flat skin.
Any time an unrehearsed spontaneous video is done sometimes points are left out. For example one has to first understand how to on a static exam determine if a plantarflexed ray is flexible. One could first hold the rearfoot in neutral some say so that the talar head is neither bulging medially or laterally and then maximally pronate the longitudinal axis of the midfoot by applying upwards pressure sub 5th metatarsal head and finally to check the range of motion of the first ray in the sagittal plane. If there is more motion available plantar to the level of the other lesser metatarsals one might just be dealing with a flexible plantarflexed ray. Then one should continue the examination by looking inside the shoe and to check for the weight distribution on the insole. If there is no depression sub first metatarsal head one can suspect a plantarflexed first ray. Because there is relative pronation of the rearfoot that occurs when the flexible plantar first ray compensates there might be a depression in the insert sub 2nd 3rd and 4th metatarsal heads. ( This occurs because relative rearfoot pronation results in hypermobility of the first ray.) In podiatric biomechanical exams one must take into consideration not only the static exam but the resulting effects on shoe gear, callous distribution, gait analysis. Finally on gait analysis one could check to see if there is relative pronation of the rearfoot that occurs if the calcaneus is pronating during the gait cycle when it should be supinating. These biomechanical concepts I learned during lectures at NYCPM approximately 1982. All my teachers in the orthopedics dept at NYCPM were very intelligent, caring and wonderful. I wish to thank every teacher I had. I am continuing to learn more every day. Furthermore, I believe that Root had an excellent textbook on biomechanics.
A lattice pattern does go over the ridges in an approximately perpendicular direction but the fibrillar pattern goes across the ridges at a diagonal pattern other than perpendicular.
If after a podiatric biomechanical gait analysis, static exam, examining the depression in the shoe gear if a flexible plantarflexed first ray is the final deformity, and if a melanocytic nevus is present with a fibrillar pattern sub first ray, in my opinion should be biopsied. The reasoning is that the flexible plantarflexed ray would not lead to enough shearing forces capable to result it the diagonal distribution of pigment across the ridges.
I wish to thank Derm Foot, Dr. Marghoob and the Atlas of Dermoscopy, the biomechanical lectures at NYCPM during 1982 and to all my teachers who I am so grateful for.
Suppose there are characteristics of milia-like cysts in seborrheic keratosis.
or shiney white structures in basal cell carcinoma, this is all the more reason to use a dermlite 4 dermatoscope with its high polarization and ability to toggle from polarized to nonpolarized. I believe it is common knowlege that milia cysts do not show up well on polarized dermoscopy and shiney white structures do not show up well using non polarized dermoscopy.
Why can’t every hospital OR be fully equipped by having dermatoscopes available to its surgeons with sterilized ice caps so as to attempt to protect the sterile field. If there is a histologic interpretation of any lesion be it inside or outside of the OR, why not consider getting a picture with a dermatoscope? This just might prove useful to the pathologist or dermatopathologist. For example a dermatoscope might be useful in distinguishing between a subungual exostosis vs an osteochondroma?The one problem I can see is maintaining sterility. The dermatoscope is not sterile. However if a sterile drape is placed over the dermatoscope and the dermlite 4 is used and the Dermlite 4 has its ice cap sterilized it just might be possible to maintain a sterile field and get a clear picture of the intraoperative area.
One concept I learned at the derm foot seminar might disagree about there being any “gold standard”. Actually the new current gold standard just might be including all your history of skin cancer or family history of skin cancer, exam clinical date including dermoscopic imaging as well as biomechanical exam, shoe gear analysis as well as biopsy report. In a different post I gave an opinion that a biopsy report of a shave into the papillary dermis that said the lesion was benign just might benefit from a dermatoscopic image which might possibly capture structures beneath the papillary dermis depending upon the dermatoscope used. A benign report from a dermatopathogist regarding a superficial shave biopsy that only examines the papillary dermis just might not be that gold of a standard to soley rely on if a polarized dermoscopy image read by the podiatrist sees suspicious structures.
After reading the above I am making another conclusion:
Usually shave biopsies are used in the dorsum of the foot. If polarized dermatoscope shows suspicious structures on the dorsum of the foot then perform a punch biopsy. Dermoscopy is needed to tell what is the best biopsy method to use for dorsal lesions either a shave vs a punch or both a shave and a punch biopsy.
Biopsies can be indeterminate. On should correlate all the information available including dermoscopy. If a pathology report comes back as indeterminate, having a dermatoscopic image is helpful in finalizing the diagnosis. Dermoscopy is only one factor used in diagnosing problems. There is shoe pathology, etc… In this day and age where dermatoscopes are readily available and textbooks are out there why deprive a patient of access to such advanced imaging?
There is a difference between a magnified clinical picture of a toenail and a dermatoscopic image. One needs a dermatoscope with enough polarization or direct contact with an ultrasonic gel or clear gel.
Also, the need for polarization in the nails is not really needed as much as the proper contact medium and this should be an ultrasound gel.
I also learned at Derm Foot that is there is subcorneal hemorrhaging a ridge pattern on the bottom of the foot that is benign. If the blood can be scraped off and normal skin is beneath even if on a ridge it is benign. My opinion is that this concept also should extend to the toenail bed. If the blood can be scraped off and there is normal skin beneath on the toenail bed this is not a sign of a subungual melanoma.
In all due respect dermoscopy in podiatry is being used routinely by some. Just because podiatrists do not post about it here it is quite possible that as lot of podiatrists are using dermatoscopes. I am however devoting a lot of time towards learning this. I have 3 scopes and currently only make use of 2 of them. As technology improves one just may decide to upgrade their dermatoscope to one with a higher degree of polarization.
The Derm Foot seminar only was an introduction. The seminar emphasized mainly nails and the lesions on the glabrous skin on the plantar feet. I am attempting to dive deeper into structural analysis above Wallace’s line. There is so much to learn.
For example, how does one know if a Micro- Hutchensons sign is present without a dermatoscope? I learned about this from Derm-foot lectures. Now this is a hint. The archives of Dermatology can further expand upon this. How can podiatric residency training be comprehensive if a microhutchenson’s sign is missed because a teaching program does not have a dermatoscope? If podiatry residency programs are supposed to prepare residents with being able to sit for the ABPM certification exam and if the ABPM certification exam might possibly in the future cover the subject matter of dermoscopy then why not have every podiatric residency program in the country have the availability of highly polarized dermatoscopes?
Please go online and look up the word Dermatoglyphics. You probably will conclude the plantar aspect of the feet have dermatoglyphics or ridges present. I like to refer to the plantar skin that consists of skin without ridges and skin with ridges.
The article in Podiatry Today regarding Acral Lentiginous Melanoma referred to the plantar skin I believe as consisting of ridges and furrows.
The following is a brief explanation of concepts I learned at the Derm Foot Seminar:
Parallel furrow pattern is no pigment crosses over the ridges.
Lattice pattern some pigment crosses over the ridges in basically a perpendicular direction
Fibrillar pattern is pigment crosses over the ridges diagonally.
If any of the patterns are irregular and not consistent then one should consider taking a biopsy. I did not learn about an irregular lattic pattern and I am guessing that it does exist. MY ONE REQUEST IS IF ANYONE EVER SEEN AN IRREGULAR LATTICE PATTERN PLEASE COMMENT ON THIS.
This is discussed in many online sites. I think of a fingerprint on the hand or a foot print. Fingerprints have ridges which follow a certain pattern. The plantar ( or acral ) surfaces of the feet have ridges.
Please go online and look up the word Dermatoglyphics. You probably will conclude the plantar aspect of the feet have dermatoglyphics or ridges present.
At a certain level on the foot the dermatoglyphics begin to stop. This is called Wallace’s Line. This I learned at the Derm Foot Seminar. This is one reason why I am advocating that podiatrists go to the Derm Foot Seminar and the they consider purchasing the Atlas of Dermoscopy mentioned earlier.
Proximal to Wallace’s line one can the 3 point check list that emphasizes if a lesion is asymmetric, has an atypical network, or has blue white structures. Dermoscopy the Essentials explains this quite clearly.
The Dermlight 4 has a strong polarization and pigment boost and a toggling function that in my opinion has state of the art in acquiring clear images.