I learned from the Derm Foot Lecture from Dr. Marghoob in Maryland approx. 2006 that on the arch of the foot there is mainly a lattic type pattern, the weight bearing part of the foot there is the fibrillar pattern and in between there is a furrow pattern. One can conclude that if one sees the fibrillar pattern on a non weight bearing area of the foot it needs to be biopsied. I learned from Dr. Marghoob’s lecture in Maryland approx. 2016 and the atlas of dermoscopy that shearing forces from weight bearing areas can cause a fibrillar pattern.
The examining the anatomic location of a lesion is only part of the information available. There is also biomechanical information available that I believe should be also considered with the dermatoscopic results.
The problem is that it is not so simple understanding where the weight bearing areas of the feet are unless a full biomechanical and gait analysis is performed to determine which parts of the foot are most susceptible to shearing forces. THE ANATOMIC LOCATION ON THE FOOT IS NOT THE ONLY FACTOR IN DETERMINING THE SUSCEPTIBILITY TO SHEARING FORCES. THERE ARE BIOMECHANICAL FACTORS AS WELL FROM BIOMECHANICAL FAULTS DETERMINED BY ONES STATIC EXAM AND GAIT ANALYSIS. The following biomechanical example is not something mentioned at the seminar but what I learned at NYCPM back in 1982.
One example is a lesion on the plantar aspect of the first metatarsal head area. As we all know the compensation occurs on the frontal and saggital planes as a suponatory rock of the rearfoot and a lot of pressure is on the plantar aspect of the first metatarsal head thus a benign fibrillar pattern as seen on the dermoscopy exam.
Yet if the biomechanical fault is flexible the saggital plane compensation of the plantarflexed first ray is dorsiflexion and less pressure results under the first metatarsal ray and therefore a lattice type lesion instead of a fibrillar dermatoscopic pattern all other factors being constant.
Thus if one sees a benign fibrillar pattern one just might not worry so much if the plantarflexed first ray deformity is rigid vs be it a flexible deformity. If one finds a fibrillar pattern on the plantar aspect of a flexible plantarflexed first ray then one just might need to biopsy this lesion. This is one example why I feel that all biomechanical exams both static exams and weightbearing exams must include dermoscopy. Also all pedal dermoscopy exams of the feet must include biomechanical gait analysis as well as static exams of the lower extremities.
I wish to thank Dr. Marghoob for opening my eyes and getting me even more interested in dermoscopy. Again I believe that full biomechanical exams should also consider including the dermatoscopic examination of pedal lesions.