Sir,
Hypertrichosis is the growth of excessive hair anywhere on the body. This is frequently confused with hirsutism, which is excessive growth of terminal hairs in androgen-dependent sites. Hypertrichosis can be classified based on its distribution (localized versus generalized), type of hair (lanugo or vellus versus terminal), and the age of onset (congenital or programmed from birth versus acquired).
A 26-year-old female presented with increased hair growth over the left forearm. She had a history of trauma leading to a fracture of the left forearm bone [Figure 1]. For this reason, she was treated by an orthopedic surgeon. Fiberglass cast was applied below the elbow for 6 weeks. After cast removal, increased hair growth was noted over the fracture site. The patient had a known case of nutritional deficiency anemia. There was no drug history except analgesics and hematinics. There was no history of topical application. On cutaneous examination, there was an increase in both coarse and fine hair over the distal forearm compared to the contralateral site [Figures 2 and 3]. No hypertrichosis was noted on the rest of the body. On systemic examination, pallor was noted. In routine blood investigation, hemoglobin (Hb) level was low (Hb - 7.2 g/dL). The rest of the laboratory investigations were within the normal limits. The patient was followed up monthly. After 5 months, spontaneous resolution of hypertrichosis was noted [Figures 2 and 3].
Figure 1.
Distal radius fracture with intra-articular extension
Figure 2.
Dorsum of the left hand and distal forearm showing hypertrichosis, resolution of hypertrichosis after 5 months
Figure 3.
Flexure of the left distal forearm showing hypertrichosis, resolution of hypertrichosis after 5 months
Majority cases of localized hypertrichosis involve a switch from vellus to terminal hair. Transient localized hypertrichosis has been observed within vaccination sites and varicella scars as well as sites of wart removal and laser epilation.[1] In addition, hypertrichosis has been described as overlying lipoatrophy following lupus panniculitis and within resolving lesions of psoriasis and morphea. Localized hypertrichosis has been reported after psoralen plus ultraviolet A (PUVA) therapy.[2] Sites of application of potent topical corticosteroids, tacrolimus, and creams containing mercury or iodine can also develop localized hypertrichosis, as can sites of repeated irritation from anthralin. Prostaglandin F-2α analogs (e.g., latanoprost, bimatoprost) were noted to induce trichomegaly of the eyelashes.
Acquired localized hypertrichosis arises after chronic irritation, friction, repeated trauma, or inflammation (e.g., hypertrichosis in areas of the crutch friction, hypertrichosis in areas of the cast application after fracture, hypertrichosis of posterior aspect of the neck in heavyweight lifters). Cutaneous hyperemia and heat are stimulants of hair follicles.[3] Chronic venous insufficiency or inflammation of joints leading to cutaneous hyperemia also causes hypertrichosis. Trauma increases regional blood flow and metabolism on the part of all local soft tissues, termed “regional acceleratory phenomenon,” proposed by Frost. Chronic irritation of the skin under the cast leading to hyperemia remains another factor responsible for hypertrichosis.[4] Other authors also reported that cutaneous hyperemia may be responsible for hypertrichosis following cast application for fracture.[4,5] This cutaneous hyperemia is a transient phenomenon. Thus, it may be responsible for transient hypertrichosis. Our patient showed spontaneous resolution of hypertrichosis after 5 months. However, no studies are showing histological data to confirm this.
All dermatologists should be aware of the transient and benign course of acquired localized hypertrichosis following cast application for fracture. Due to such a transient course, further investigations are not indicated.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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