Canities Subita after Extreme Trauma Showing Positive Staining for Anti-PD-L1 Antibodies: A New Clue into Etiopathogenesis?

Abstract

Canities subita has been considered by some authors an acute episode of diffuse alopecia areata in which the sudden whitening is caused by the preferential loss of pigmented hair in this immune-mediated disorder. Clinically, the “salt and pepper” pattern of hair color is the most frequent manifestation of canities subita. However, the exact physiopathology of canities subita is not completely understood. A 69-year-old Caucasian man was referred for the sudden and asymptomatic whitening of the hair on the scalp and eyebrows, without an associated hair loss. The trigger was the death of his brother. Hair whitening appeared 24 h after the event. He reported a history of alopecia areata in plaques on the scalp, with spontaneous complete resolution in 2006. The physical examination showed full whitening hair on the scalp and eyebrows. Eyelashes were not affected. The pull test was negative, and the patient denied a significant hair loss in the last days. The histopathological study showed several follicle-sebaceous structures in the anagen, and one of them (inset) with a transforming hair bulb. The anterior bulb was surrounded by a lymphocytic inflammatory infiltrate in an advanced stage of transformation to the catagen and incipient scar changes. Immunohistochemistry staining showed a positive anti-PD-L1 antibody expressed in the inflammatory infiltrate. Based on the clinical and histological findings, a diagnosis of canities subita was made. The histopathological study showed a positive staining for anti-PD-L1 antibodies, supporting the role of the immune system in the development of this phenomenon. The interaction between melanogenesis and the lymphocytes warrants further research.

Established Facts

• Sudden bleaching of the hair is known as sudden canities.

• Some authors consider the canities subita as a form of alopecia areata.

Novel Insights

• Positive anti-PD-L1 antibody staining has not been studied in depth in alopecia areata.

• Staining with anti-PD-L1 antibodies is related to the pathophysiology of vitiligo.

• It is possible that the physiopathological mechanism of sudden canities is related to that observed in patients with vitiligo.

Introduction

The phenomenon of night graying refers to the sudden whitening of the hair in a short period. This entity is known as a canities subita [1], and almost 200 cases have been reported to date. The English author of Utopia Sir Thomas More suffered a similar condition in 1535. The most famous historical report of sudden graying was Queen Marie Antoinette of France before her death in the guillotine. Some authors attributed this phenomenon to a diffuse alopecia areata [2], although the exact mechanism remains unclear. We describe a case of canities subita showing positive staining for anti-PD-L1 and discuss its potential implication in the pathogenesis of this entity.

Case Report/Case Presentation

A 69-year-old Caucasian man was referred for the sudden and asymptomatic whitening of the hair on the scalp and eyebrows, with a moderate loss of follicular units. The trigger was the death of his brother. Hair whitening appeared 24 h after the event. The patient denied the use of bleaches or other hair cosmetics. He reported a history of alopecia areata in plaques on the scalp, with spontaneous complete resolution in 2006. His personal history consisted of hypertension, type 2 diabetes mellitus, dyslipidemia, chronic pulmonary obstructive disease, and atherothrombotic occlusion of the left internal carotid artery. The physical examination showed full whitening hair on the scalp and eyebrows (Fig. 1a–d). Eyelashes were not affected (Fig. 1e, f). The pull test was negative, and the patient denied a significant hair loss in the last days. The histopathological study showed several follicle-sebaceous structures in the anagen, and one of them (inset) with a transforming hair bulb (Fig. 2a, b). The anterior bulb was surrounded by a lymphocytic inflammatory infiltrate in an advanced stage of transformation to the catagen and incipient scar changes (Fig. 2c). Immunohistochemistry staining showed positive CD8 lymphocytes and anti-PD-L1 antibody expressed in the lymphocytes that infiltrated the hair follicle (Fig. 2d). Based on the clinical and histological findings, a diagnosis of canities subita in the context of alopecia areata was made. After discussing the prognosis with the patient, an expectant attitude was taken. After 12 months of follow-up, a spontaneous repigmentation showing the characteristic pattern in “salt and pepper” was observed (Fig. 2e, f), clinically the same as before the episode of canities subita. Immunohistochemistry staining from PD-1 and HMB45 is shown in Figure 3.

Fig. 1.

a–d Full whitening hair on the scalp and eyebrows. e, f Eyelashes were not affected.

Fig. 2.

a (H&E. ×1) Cutaneous punch with several follicle-sebaceous structures in the anagen, and one of them (inset) with a transforming hair bulb. b (H&E. ×10) The anterior bulb surrounded by a lymphocytic inflammatory filtrate in an advanced stage of transformation to the catagen and incipient scar changes. c (H&E. ×20) Detail of another follicular bulb with intense inflammatory infiltrate. d (PD-L1) Staining of the anti-PD-L1 antibody expressed in the inflammatory infiltrate. e, f Pattern in “salt and pepper.” Almost complete repigmentation.

Fig. 3.

a The existence of T cells expressing PD-1 around a bulb, and the bulb cells expressing PD-L1, as illustrated in the manuscript. b The HMB45 (gp100) stain shows no positivity in follicular cells, with internal positive control in the epidermis. This absence of melanocytes in bulbs must be researched.

Discussion/Conclusion

Canities subita has been considered by some authors an acute episode of diffuse alopecia areata in which the sudden whitening is caused by the preferential loss of pigmented hair in this immune-mediated disorder [2]. Clinically, the “salt and pepper” pattern of hair color is the most frequent manifestation of canities subita [3]. However, the exact physiopathology of canities subita is not completely understood. Authors such as Metchnikoff [4] suggested the presence of pigmentophages, although this hypothesis could not be proven. Trauma, shocking ordeals, severe threats, or psychological upheavals may be the triggers of this phenomenon. Some reasons make believe that canities subita is a special type of diffuse alopecia areata [2]. The histopathological study carried out in our patient showed an inflammatory infiltrate around the follicular unit. Positive staining for anti-PD-L1 antibody raises the suspicion of the role of the lymphocytes in the development of this phenomenon. Canities subita could be related to follicular melanocyte autoimmune impairment which could explain the preferential follicular pigment, such as reported in follicular vitiligo [5]. Authors have suggested an early reduction in tyrosinase activity within hair bulb melanocytes associated with inappropriate melanocyte cortical keratinocyte interactions and defective migration of melanocytes to the hair bulb [6]. Nishimura [7] reported that the analysis of mutant Bcl₂-deficient mice revealed that the loss of melanocyte stem cells precedes the loss of hair matrix melanocytes and hair graying. The interaction between the immune system and follicular melanocytic cells seems to play an interesting role in the development of canities subita [8]. However, its complexity has not allowed a concrete explanation to be found.

Nahm et al. [9] reported a reappraisal of 196 cases of canities subita, of whom 44 cases were authenticated. Poliosis was the most frequent associated disease. Two patients showed vitiligo and 6 patients associated nonscarring alopecia. Scalp hair was the most common affected area, followed by eyelashes and beard.

Reports on hair repigmentation have been notified after the use of some drugs such as thalidomide, lenalidomide, erlotinib, and adalimumab. These drugs may act through the inhibition of pro-inflammatory cytokines that have an adverse regulation effect on melanogenesis. Anti-PD-1 drugs (nivolumab and pembrolizumab) and anti-PD-L1 drug (atezolizumab) have associated follicular repigmentation during its use in the treatment of lung cancer [10]. Paradoxically, cases of alopecia areata induced by pembrolizumab [11] and PD-1 inhibitor drugs [12] have been reported. This phenomenon confirms the complexity of the interaction between the immune system and the melanogenesis and human hair biology.

Antigen presenting cells and parenchymal cells expressing PD-L1 (family of ligands B7 and CD274) act as a physiological mechanism that induces immune tolerance and tissue protection. PD-1 (CD279+) is a molecule expressed on the cell surface of T lymphocytes. The binding of PD-1 to PD-L1 constitutes one of the immunological inhibitory pathways whose function is to maintain immune tolerance and prevent the development of autoimmune diseases. Melanocytes express PD-L1 on their cell membrane [13]. PD-L1 expression in the melanocyte may increase after secretion of pro-inflammatory cytokines such as INF-gamma [14]. As observed in tumors such as melanoma, the secretion of INF-gamma by tumor-infiltrating lymphocytes increases the expression of PD-L1, causing a dysfunction of T lymphocytes through the PD-1 pathway, a situation known as “adaptive immune resistance.” Immune suppression requires the binding of PD-1 (expressed in T lymphocytes) to its ligand PD-L1 (expressed in dendritic cells and macrophages, among others). This cellular signaling induced by the binding of PD-1/PD-L1 represses the activation and function of autoreactive T lymphocytes, inhibiting their proliferation and inducing apoptosis. With this, the phenomenon of immunological tolerance previously commented is observed. The absence of PD-1 expression reduces antigen recognition and increases the cytotoxic activity of CD8⁺ T lymphocytes. The altered function of PD-1/PD-L1 has been demonstrated in autoimmune diseases such as type 1 diabetes mellitus, inflammatory bowel disease, psoriasis, or rheumatoid arthritis.

PD-L1 can be expressed in melanocytes, especially in situations of inflammatory response, such as vitiligo. For this reason, it is questioned whether the use of immunotherapy against PD-1 or PD-L1 could induce peripheral immune tolerance, from which vitiligo could benefit [15]. In vitiligo, there is an inflammatory infiltrate of CD8⁺ lymphocytes, which secrete INF-gamma, a cytokine that induces the expression of PD-L1 in the melanocyte. Furthermore, vitiligo patients show increased expression of PD-1 on CD3⁺/CD4⁺ T lymphocytes and peripheral regulators, suggesting that PD-1 could play an important role in the pathogenesis of the disease. There is a positive correlation between vitiligo activity and CD8⁺/PD-1 lymphocyte expression. With these data, the authors considered the treatment of vitiligo with immunotherapy directed at the PD-1/PD-L1 axis [16]. They even proposed the combination of these drugs with UVB-NB phototherapy, which has been shown to increase the expression of PD-L1 in melanocytes.

As has been described in vitiligo, it is possible that the development of sudden canities as a variant of alopecia areata presents a similar pathophysiological mechanism, where the melanocyte is the main cell affected by immune dysfunction mediated by the PD-1/PD-L1 axis, while the keratinocytes of the hair follicle are not affected, and therefore hair loss is not the main clinical sign observed. Excessive activation of autoreactive CD8⁺ T lymphocytes and decreased function of regulatory CD4⁺ T lymphocytes could be achieved by PD-1/PD-L1 signaling interference.

Although more studies are still needed, the PD-1/PD-L1 axis appears to be one of the important mechanisms in peripheral immune tolerance. B lymphocytes, fibroblasts, keratinocytes, and dendritic cells express PD-L1. The development of agonists of the PD-1/PD-L1 axis could suppress reactive T lymphocyte melanocytes and concomitantly suppress regulatory T lymphocytes. Furthermore, treatment with PD-L1 agonists would increase the recruitment of regulatory T lymphocytes (FoxP3) locally in the affected areas, avoiding the depigmentation observed in vitiligo. This type of immunotherapy could be a therapeutic target for vitiligo, and even alopecia areata. However, future studies will be needed to prove this hypothesis.

In conclusion, we present a case of canities subita in the context of alopecia areata after extreme trauma. The histopathological study showed a positive staining for anti-PD-L1 antibodies, supporting the role of the immune system in the development of this phenomenon. The sudden bleaching of the hair could be caused by the involvement of melanocytes reactive to T lymphocytes, mediated by the immune dysfunction signaled by the PD-1/PD-L1 pathway. The interaction between melanogenesis and the lymphocytes warrants further research.

Statement of Ethics

Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Conflict of Interest Statement

The authors have no conflicts of interest to declare.

Funding Sources

No funding sources were used in this work.

Author Contributions

Francisco J. Navarro-Triviño: conceptualization-lead, data curation-lead, formal analysis-lead, investigation-lead, methodology-lead, writing − original draft-lead, and writing − review and editing-lead. Ricardo Ruiz-Villaverde: conceptualization-equal and writing − original draft-supporting. Francisco Manuel Ramos-Pleguezuelos: conceptualization-equal. Sergio Vañó-Galván: conceptualization-equal and writing − original draft-supporting.