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Localized hypertrichosis following tacrolimus therapy: A case report and brief review

Dear Editor Oral tacrolimus is a mainstay of immunosuppression following solid organ transplantation. In cells, tacrolimus binds a cytoplasmic receptor to form a complex that competitively inhibits calcineurin, ultimately reducing the transcription of cytokines including interleukin-2 and impairing proliferation of T lymphocytes. Cyclosporine is another calcineurin inhibitor used to prevent organ transplant rejection and immune-mediated diseases including rheumatoid arthritis and psoriasis. Hypertrichosis is an established side effect of cyclosporine, but is seldom reported with tacrolimus. Herein, we describe a case of malar hypertrichosis developing soon after initiating systemic tacrolimus. A 53-year-old man presented to dermatology clinic 6 weeks after undergoing orthotopic heart transplantation for ischemic cardiomyopathy. He described recent hair growth on his upper cheeks. Physical examination revealed bilateral hypertrichosis with dark terminal hairs overlying the temporal and zygomatic areas of the face with background hyperpigmentation (Figure 1A-C). The patient's immunosuppression regimen consisted of tacrolimus 6.5 mg, mycophenolate mofetil (MMF) 3 g, and prednisone 14 mg daily. The hypertrichosis in our patient is most likely secondary to tacrolimus given the timing of initiation of therapy and quick onset of hair growth, in conjunction with biologic plausibility. Still, reports of hypertrichosis secondary to tacrolimus are rare. In a randomized clinical trial comparing the side effects of tacrolimus and cyclosporine in renal transplant patients, hypertrichosis was observed in 0.6% of patients on tacrolimus compared to 8.9% on cyclosporine. A review of the literature revealed three additional reports of hypertrichosis attributed to topical or systemic tacrolimus (Table 1). Two of the three cases reported focal hypertrichosis or eyelash trichomegaly following topical 0.1% tacrolimus applied daily or twice daily for vitiligo. (Table 1). In the third case, eyelash trichomegaly was observed following systemic tacrolimus, dose unspecified, for orthotropic heart transplantation (Table 1). We now describe another case of hypertrichosis involving the malar region that developed shortly after commencing systemic tacrolimus. The patient's tacrolimus trough blood level was within target therapeutic range at 14.7 ng/mL. In two of the reviewed cases and in our patient, excess hair growth was first noticed within the first 2 months of treatment. The remaining case of trichomegaly following topical tacrolimus developed after 8 years of consistent use (Table 1). None of the reviewed cases reported treatment for excess hair. We offered our patient reassurance and discussed depilatory and epilatory options which he declined.