Syphilitic nail dystrophy: Two case reports

Dear Editors, Syphilis is known for its atypical clinical presentations, posing challenges to accurate diagnosis. This report highlights uncommon nail changes in two cases of syphilis that posed clinical diagnostic difficulties. These nail changes, occurring alongside papulosquamous lesions, may be easily overlooked. Case 1 is a 30-year-old man undergoing treatment for diffuse large B-cell lymphoma of the tonsils who had progressive skin and nail lesions during the chemotherapy. Initially, the patient had erythematous plaques diffusely on the palms and soles following the fourth course of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone. A chemotherapy-induced hyperkeratotic hand–foot syndrome was diagnosed. However, despite 4 months of treatment with topical steroids, urea lotion, oral steroids, and cyclosporine, the lesions persisted and further progressed. Eight months after the initial skin presentation, he developed multiple erythematous plaques with variable hyperpigmented patches on the chest, trunk, and limbs, along with prominent nail dystrophy of all finger and toe nails Figure 1a. Two incisional biopsies were performed on the chest and wrist, which showed lichenoid psoriasiform dermatitis with numerous spirochetes present, confirmed by Treponema pallidum immunohistochemical stain. Subsequent blood tests revealed reactive rapid plasma reagin (RPR) (1:1024) and treponemal test (29.68 sample/cutoff) results. Human immunodeficiency virus testing was negative. The patient received doxycycline 100 mg twice daily for 2 weeks as an alternative treatment owing to amoxicillin allergy. There was rapid improvement in the skin and nail lesions Figure 1b and c. Chemotherapy was eventually resumed and completed. Five years later, the patient had no evidence of recurrent lymphoma and all skin and nails kept normal.Figure 1: The nail changes before and after therapy for syphilis in case 1. (a) Before therapy, there was swelling of the proximal nail folds with thick yellowish and hemorrhagic crusts overlying the nail plate. The distal-free edge of the nail plate appeared brittle and thinned out, (b) A decrease in the swelling of the proximal nail folds was observed 2 weeks after the completion of oral doxycycline, (c) Six weeks after therapy, the nail plates of the fingernails were thinning with normal nail plate appearing in the proximal end of the nails.Case 2 is a 35-year-old man with a 2-month history of thick, yellowish scaling on the scalp, scattered erythematous macules, and patches on the face, inguinal area, and scrotal area. Nail pitting, onycholysis, and salmon patches were observed on the fingernails Figure 2. The patient's brother had psoriasis. An incisional biopsy was performed on the right thigh under the impression of psoriasis with nail involvement, which revealed lichenoid psoriasiform dermatitis with numerous spirochetes in the epidermis for the T. pallidum immunohistochemical stain. The patient tested reactive for RPR (1:128) and the treponemal test (23.74 sample/cutoff), with a negative result for human immunodeficiency virus. Treatment with benzathine penicillin G was initiated, leading to improvement in the nail changes during the 2nd month of follow-up. Complete resolution of all nail abnormalities was achieved after 6 months.Figure 2: Nail changes in case 2. (a) The left thumb showed transverse splitting and grooves toward the free edge, (b) The fingernails on the left hand had oil spots, focal onycholysis, and salmon patches. There was a central groove on the fingernail of the third digit resembling koilonychia or onychomadesis, (c) Erythematous nodular swelling on the third and fourth digit of the left hand indicated paronychia and onychomadesis.Syphilis-associated nail changes were rare and were first described as "syphilitic onychia" by Macleod in 1910,1 subsequently recognized across all stages of syphilis.2,3 These changes can present similarly to psoriasis or lichen planus.2 The spectrum of nail changes associated with syphilis includes paronychia, trachyonychia, onychoschizia, onychomadesis, nail pitting, onycholysis, and onychoptosis.2-4 Notably, nail involvement may sometimes be the sole manifestation of syphilis.3 Previously reported syphilis cases with nail changes cases were typically diagnosed through skin biopsy of papulosquamous lesions and/or serologic treponemal and nontreponemal tests.4 Lesions affecting the nail folds and nail bed were mostly not biopsied, as observed in our two patients. Skin biopsies of syphilis often exhibited psoriasiform dermatitis with a band-like lichenoid mixed cell infiltration.5 It may explain why nail changes clinically resemble those seen in lichen planus and psoriasis. Nail changes usually show improvement a few months after treatment. However, chronic inflammation poses a risk of permanent damage to the nail matrix, potentially resulting in anonychia. Fortunately, both of our patients achieved complete recovery following appropriate management. In conclusion, the diagnosis of syphilis depends on clinical and pathological indicators. Nail changes associated with syphilis may mimic other inflammatory disorders of the nails, potentially leading to oversight. Syphilis should be actively excluded in such scenarios to ensure accurate diagnosis and correct therapy. Ethical approval This study was conducted in accordance with the Declaration of Helsinki and was approved by the IRB of MacKay Memorial Hospital (approval number: 24MMHIS002e), approved on Jan 29, 2024. The patient consent was waived by the IRB. Data availability statement The datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable request. Financial support and sponsorship Nil. Conflicts of interest Dr. Yu-Hung Wu, an editorial board member at Dermatologica Sinica, had no role in the peer review process of or decision to publish this article. The other author declared no conflict of interest in writing this paper.