Dermatology: Practical and Conceptual Image Letter | Dermatol Pract Concept. 2024;14(1):e2024024 1 Fox Tail Like Furry Appearance in a Case of Black Hairy Tongue Parul Kamboj1, Preema Sinha1, Choudhary Sampoorna Raj1, Prashantha G B1, Akansha Tripathi1 1 Department of Dermatology, Base hospital Lucknow (Uttar Pradesh), India Citation: Kamboj P, Sinha P, Raj CS, Prashantha GB, Tripathi A. Fox Tail Like Furry Appearance in a Case of Black Hairy Tongue. Dermatol Pract Concept. 2024;14(1):e2024024. DOI: https://doi.org/10.5826/dpc.1401a24 Accepted: May 20, 2023; Published: January 2024 Copyright: ©2024 Kamboj et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding author: Dr Choudhary Sampoorna Raj, Department of Dermatology, Base hospital Lucknow (Uttar Pradesh), India. Phone: (+91) 7004913218 E-mail: csr8711@gmail.com Acknowledgement: The patient in the manuscript has given written informed consent to the publication of case details and photographs. Case Presentation A 22-year-old Indian male, non-smoker, a known case of non-Hodgkin B-cell lymphoma, subtype diffuse large B-cell lymphoma, developed dark discoloration of the dorsum of the tongue, with dysgeusia, metallic taste, and halitosis two weeks after undergoing an autologous stem cell transplant and being started on prophylactic Tab Penicillin G and Tab Acyclovir [1]. The discoloration was insidious in onset and progressed over 20 days to involve the majority of the ante- rior two thirds of the tongue. Examination of oral mucosa revealed a brownish to black-colored furry tongue predom- inantly involving the anterior two-thirds of the tongue an- terior to the circumvallate papillae, with relative sparing of the tip and lateral borders (Figure 1A). No significant pigmentation was noted at any other site. The KOH mount revealed no fungal hyphae, and the culture revealed no growth. Dermoscopy was performed which revealed charac- teristic findings (described below). The patient was advised to practice regular tongue brushing and maintain proper oral hygiene, which led to regression of elongated papillae and resolution of symptoms in 2 weeks. Teaching Point Dermoscopic examination revealed yellowish‐brown and brownish‐black furry projections (elongated filiform papillae) resembling ‘Fox tail’ (green arrow), white globular areas (red arrow) over a pinkish background (black arrow) resembling rose petals. A distinct color variation was also appreciated in individual filiform papillae, with the base being a lighter shade than the tip (blue arrow) (Figure 1B). 2 Image Letter | Dermatol Pract Concept. 2024;14(1):e2024024 References 1. Akay BN, Sanli H, Topcuoglu P, Zincircioğlu G, Gurgan C, Heper AO. Black hairy tongue after allogeneic stem cell transplan- tation: an unrecognized cutaneous presentation of graft-versus- host disease. Transplant Proc. 2010;42(10):4603-4607. DOI: 10.1016/j.transproceed.2010.09.177. PMID: 21168745. 2. Sil A, Panigrahi A. “Sea Anemone” Appearance in Dermoscopy of Black Hairy Tongue. Indian Dermatol Online J. 2021;14(4):580- 581. DOI: 10.4103/idoj.IDOJ_58_21. PMID: 37521216. PMCID: PMC10373830. Figure 1. (A) Revealed a brownish to black-colored furry tongue predominantly involving the anterior two-thirds of the tongue anterior to the circumvallate papillae, with relative sparing of the tip and lateral borders. (B) Revealed yellowish‐brown and brownish‐black furry pro- jections (elongated filiform papillae) resembling ‘Fox tail’ (green arrow), white globular areas (red arrow) over a pinkish background (black arrow) resembling rose petals. A distinct color variation was also appreciated in individual filiform papillae, with the base being a lighter shade than the tip (blue arrow).