Title : Optimal depth of bipolar radio frequency penetrance to achieve therapeutic results for the treatment of axillary hyperhidrosis and the first reported histopathological evidence of apoeccrine gland’s seminal role in the pathophysiology of axillary hyperhidrosis
Abstract:
Introduction: Bipolar radio frequency (RF) is a minimally invasive, non-surgical and non- pharmacological systemic dermatological procedure for skin contouring, tightening, and restoration of photodamaged skin. RF has also shown to be effective in the treatment of axillary hyperhidrosis (AH). The exact therapeutic mechanism, targeted micro-anatomical structures and depth penetrance not yet fully elucidated.
Objective: The aim is to evaluate histopathological effects of and clinical outcomes from RF-MN in treating AH.
Methods: Limited data set with three individuals with severe AH were treated with a series of 3 passes at 4-week interval spanning a total of three months with RF with micro needling (MN) with set penetration at a depth of 2.5 mm. The treatment naive and post treatment areas were biopsied and the tissue specimens processed for conventional histopathology evaluation.
Results: All three patients failed to report and achiever therapeutic clinical improvement. One patient reported worsening of signs and symptoms of AH and declined post treatment biopsy. Histopathology reveal RF-MN ablative effective to a depth of 2.5-3.0mm. The eccrine straight ducts in the mid-reticular dermis were affected with dropout in the absolute number of ducts: patient A 5 to 2 and patient C 4 to 1. The eccrine and apocrine glandular component situated at a depth of 3.5-4.0mm were unaffected by RF-MN. To achieve therapeutic effect, the sweat production glandular units must be affected by RF-MN and with the corresponding penetrance depth. As a response to the eccrine straight duct destruction by RF, a compensatory reactive apoeccrine gland metaplasia was noted. There was a significant shift in the ratio apoeccrine gland to total glandular components from naive state to post treatment state with ratios of 1:4 to 1:1 and 1:2 to 1:1. Although RF-MN set at 2.5-3.0mm reached the level of the eccrine straight ducts, the compensatory increase in apoeccrine glands and sweat production nullified the benefits gained from the destruction of the ducts and failed to achieve therapeutic response.
Conclusion: Optimal therapeutic RF-MN penetrance is thus determined to be at 3.5- 4.0mm which corresponds location of the main perspiration production micro-anatomical structures of eccrine and apocrine glands. In response to RF-MN effacement of eccrine straight ducts, reactive apoeccrine gland metaplasia is discovered and quantified for the first time in modern medical literature. The apoeccrine gland produce sweat at a higher rate and volume than both the eccrine and apocrine components. The increase in flow and volume of sweat produced by the apoeccrine glands thus negated the treatment effects of RF-MN set at suboptimal depth. In addition, this is the first time in which histopathological quantitative analysis isolated apoeccrine gland as playing a key role in the pathophysiology of axillary hyperhidrosis.
