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Year : 2022  |  Volume : 67  |  Issue : 6  |  Page : 835
Postsurgical transient hypertrichosis around healing wound after total knee arthroplasty: A case report

1 Institute of Dermatology, Department of Medical Services, Ministry of Public Health, Bangkok, Thailand
2 Institute of Dermatology, Department of Medical Services, Ministry of Public Health, Bangkok; Master of Science Program in Dermatology and Dermatosurgery, Rangsit University, Pathum Thani, Thailand

Date of Web Publication23-Feb-2023

Correspondence Address:
Chinmanat Lekhavat
Institute of Dermatology, 420/7 Rajvithi Road, Rajthevee, Bangkok 10400
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijd.ijd_661_21

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Hypertrichosis is a condition characterized by the presence of an abnormal increase in the number of hairs and either occurs in a localized pattern or a generalized pattern. Localized hypertrichosis around a healing wound is an infrequent postsurgical complication. A 60-year-old Asian man came for a consultation because of an increase in the amount of hair around his 2-month postsurgical wound of right knee arthroplasty. Neither history of topical medications nor systemic medications, which can cause hypertrichosis, were presented. A diagnosis of postsurgical hypertrichosis was made clinically without any laboratory investigations. The patient was reassured that the medication was not necessary and he was appointed for follow-ups. Within the next 4 months, the hypertrichosis resolved spontaneously without any treatment. The case demonstrates the correlation between wound healing and hair morphogenesis, especially as both processes involve some similar growth factors and signaling molecules. Further studies might lead to discovery and better management of hair disorders.

Keywords: Abnormal hair growth, case report, hypertrichosis, knee arthroplasty, postsurgical, wound healing

How to cite this article:
Vathananai W, Lekhavat C. Postsurgical transient hypertrichosis around healing wound after total knee arthroplasty: A case report. Indian J Dermatol 2022;67:835

How to cite this URL:
Vathananai W, Lekhavat C. Postsurgical transient hypertrichosis around healing wound after total knee arthroplasty: A case report. Indian J Dermatol [serial online] 2022 [cited 2023 Mar 29];67:835. Available from:

   Introduction Top

Hypertrichosis is a rare postsurgical complication. There have been several case reports which described the development of hypertrichosis after different types of surgeries. The present report describes a patient who developed acute onset of increased hair growth surrounding the surgical wound after total knee arthroplasty (TKA) that later resolved spontaneously. The aim of this report is to illustrate the benign course of postsurgical hypertrichosis and to discuss the possible connection between wound healing and hair regeneration.

   Case History Top

A 60-year-old Asian man presented with a 1-month history of hypertrichosis around the surgical scar following TKA on his right knee. The hypertrichosis was present on both his knee and leg. Following a sports injury, the patient had undergone TKA on his right knee with no complications. He reported that he had never had much hair on either leg. Two months after surgery, the wound had healed well; however, he noticed some abnormal hair growth surrounding and below the surgical scar, extending downward to his right shin. The patient denied any history of topical medications on his right knee before and after the surgery. The only prescription drug he was taking was hydrochlorothiazide, which he had been using to treat hypertension for the past 2 years.

A physical examination revealed a vertical surgical scar without hypertrophic features surrounded by an increased amount of hair on the right knee and shin compared with the left leg [Figure 1]. The patient was reassured of the benign, temporary nature of hypertrichosis, and no medication was prescribed. A follow-up appointment was scheduled for 4 months later.
Figure 1: Both legs (a) 2-month postoperative appearance. (b) 6-month postoperative appearance. (c) 6.5-year postoperative appearance

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During the patient's second visit, the physical examination showed that the amount of hair on his right leg had decreased compared with his first visit. The thickness of the scar had also decreased [Figure 2] and [Figure 3]. At 6 months postoperatively, the localized hypertrichosis had spontaneously resolved.
Figure 2: Right knee (a) 2-month postoperative appearance. (b) 6-month postoperative appearance. (c) 6.5-year postoperative appearance

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Figure 3: Right leg (a) 2-month postoperative appearance. (b) 6-month postoperative appearance. (c) 6.5-year postoperative appearance

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   Discussion Top

Hypertrichosis is defined as excessive hair growth for an individual's age, sex, or ethnicity on an area of the body and is not compatible with the male pattern of hair distribution.[1] Hypertrichosis is categorized as either generalized or localized according to the distribution of the hair. The etiology of hypertrichosis can be categorized as either congenital or acquired. There are various causes of acquired hypertrichosis, including medications, metabolic disorders, local inflammation, infection, malnutrition, and thyroid abnormalities.[2]

Hypertrichosis is an uncommon postsurgical phenomenon. Gupta et al.[3] observed postsurgical localized hypertrichosis in 19 patients who had undergone TKA. The majority of the patients had hypertrophic scars, whereas the others had normal scars. Additionally, several case reports have described hypertrichosis around healing wounds in patients with a history of inguinal lymphadenectomy,[4] superficial parotidectomy,[5] and burn injury.[6]

Hair follicle morphogenesis requires various signaling molecules, including Wnt complexes, transforming growth factor-beta (TGF-β), and platelet-derived growth factor (PDGF).[7] TGF-β and PDGF are produced by macrophages for fibroblast activation in the proliferation phase of proper wound healing. Furthermore, angiogenesis is initiated by vascular endothelial growth factor (VEGF) upregulation, which helps bring nutrients to a healing wound. Additionally, overexpression of TGF-β1 and TGF-β2 can occur in hypertrophic scars, resulting in fibroblasts becoming more sensitive to TGF-β and PDGF. Both isoforms of TGF-β can also activate fibroblasts via Wnt complex signaling and SMAD proteins. When the wound is completely healed, the TGF-β production is stopped.[8] These proposed mechanisms of wound healing seem to be probable processes explaining the temporary hypertrichosis in the authors' patient. After the wound had healed and the growth factors stopped being produced, the hypertrichosis resolved.

Platelet-rich plasma (PRP) is autologous plasma prepared by the centrifugation of an individual's blood to concentrate platelets and proteins. PRP contains several growth factors, which are also found in the dermal papillae, whose functions are to maintain the anagen phase; these growth factors include PDGF, TGF-β, VEGF, epidermal growth factor, hepatocyte growth factor, fibroblast growth factor, and insulin-like growth factor 1.[9] Although the actual mechanism of transient hypertrichosis or hair regeneration is yet to be discovered, the clinical application of PRP in patients with androgenetic alopecia has been popular during the past decade.[9],[10] In the present case, the excess hair growth in the area of the surgical wound resolved 6 months later. It can be speculated that the growth factors derived from the high blood volume in the wound healing process contributed to this hair growth.

   Conclusion Top

Acquired hypertrichosis is a rare, temporary, and benign complication of TKA. Physicians must reassure patients that postsurgical hypertrichosis is not permanent and resolves by itself with neither medications nor procedures. The pathophysiology underlying postsurgical hypertrichosis is yet to be fully determined, and additional studies are necessary to acquire further knowledge related to hair regeneration. Nonetheless, this evidence might lead to better management of alopecia.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


We thank Angela Morben, DVM, ELS, from Edanz Group (, for editing a draft of this manuscript.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Thuraisingam T, McMichael AJ. Hirsutism and hypertrichosis. In: Kang S, Amagai M, Bruckner AL, Enk AH, Margolis DJ, McMichael AJ, Orringer JS, editors. Fitzpatrick's Dermatology. 9th ed. New York, NY: McGraw-Hill; 2019. p. 1563-5.  Back to cited text no. 1
Wendelin DS, Pope DN, Mallory SB. Hypertrichosis. J Am Acad Dermatol 2003;48:161-79.  Back to cited text no. 2
Gupta S, Gupta S, Kanwar AJ, Kumar B. Hypertrichosis surrounding scar of knee replacement surgery. J Am Acad Dermatol 2004;50:802-3.  Back to cited text no. 3
Finck SJ, Cochran AJ, Vitek CR, Morton DL. Localized hirsutism after radical inguinal lymphadenectomy. N Engl J Med 1981;305:958.  Back to cited text no. 4
Syme-Grant J, Naasan A. Post-surgical hypertrichosis. J Plast Reconstr Aesthet Surg 2006;59:1124-6.  Back to cited text no. 5
Sun ZY, Diao JS, Guo SZ, Yin GQ. A very rare complication: New hair growth around healing wounds. J Int Med Res 2009;37:583-6.  Back to cited text no. 6
Millar SE. Molecular mechanisms regulating hair follicle development. J Invest Dermatol 2002;118:216-25.  Back to cited text no. 7
Berman B, Maderal A, Raphael B. Keloids and hypertrophic scars: Pathophysiology, classification, and treatment. Dermatol Surg 2017;43(Suppl 1):s3-18.  Back to cited text no. 8
Alves R, Grimalt R. A review of platelet-rich plasma: History, biology, mechanism of action, and classification. Skin Appendage Disord 2018;4:18-24.  Back to cited text no. 9
Gupta AK, Cole J, Deutsch DP, Everts PA, Niedbalski RP, Panchaprateep R, et al. Platelet-rich plasma as a treatment for androgenetic alopecia. Dermatol Surg 2019;45:1262-73.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3]


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