Lichen Planus Follicularis Tumidus

Dear Editor,

Lichen planus follicularis tumidis (LPFT) is an extremely rare variant of lichen planus. LPFT is characterised by violaceous plaques with keratin‐filled mila‐like cysts and comedones [1]. The most common site of presentation is the retroauricular region [1, 2, 3, 4, 5]. A 51‐year‐old man, with no significant medical history, presented with an 18‐month history of asymptomatic skin changes to the bilateral post‐auricular regions.

On examination, the lesions appeared as brown to violaceous dermal plaques with follicular prominence and comedones (Figure 1). Given the clinical presentation, the initial differential diagnoses included follicular mucinosis, lupus erythematosus, cutaneous T‐cell lymphoma and pseudolymphoma.

FIGURE 1.

(a,b) shows the pre‐treatment retroauricular lesions, presenting as a violaceous plaque with follicular prominence, keratin‐filled cysts, and comedones. (c,d) shows the right and left retroauricular lesions after intralesional corticosteroid therapy, with flattening, reduced follicular prominence, and residual hyperpigmentation.

A 3 mm punch biopsy was performed. Histology showed follicular dilation and hyperkeratosis with comedonal appearances. There was an interface (lichenoid) reaction of follicular epithelium associated with lymphocyte exocytosis and sparse necrotic keratinocytes (Figure 2a). A perifollicular, dermal infiltrate of lymphocytes, histiocytes and sparse eosinophils was observed, with no evidence of lymphocyte atypia or folliculotropism (Figure 2b). No epidermal lichenoid change or epidermotropism was seen. PAS stains were negative for fungal organisms and mucin. CD3‐positive T cells predominated in the lymphocytic infiltrate, with a minor population of CD20‐positive B cells. CD123 staining did not reveal clusters of plasmacytoid dendritic cells. These findings confirmed the diagnosis of LPFT.

FIGURE 2.

(a) (H&E, ×400) Interface (lichenoid) reaction involving the follicular epithelium with lymphocyte exocytosis and necrotic keratinocytes. (b) (H&E, ×40) Follicular dilation and hyperkeratosis with a perifollicular dermal infiltrate of lymphocytes, histiocytes and sparse eosinophils.

Following the confirmation of LPFT, the patient was initiated on intralesional corticosteroid therapy. 10mg/mL triamcinolone acetonide was injected bilaterally into the post‐auricular plaques (0.5mL bilaterally). At review 10 weeks later, the right lesion had flattened considerably, while the left remained elevated. A second injection of 0.15mL was administered to the left plaque. At that visit, the right lesion demonstrated flattening, with mild residual hyperkeratosis and post inflammatory hyperpigmentation was noted in both sites. There was no evidence of extension, new lesion development or reoccurrence (Figure 1).

LPFT is a chronic, relapsing condition with limited therapeutic success, as spontaneous resolution is rare and recurrence frequently follows surgical excision [1, 5]. Reported therapies, including high‐potency corticosteroid creams [2, 4, 6], oral corticosteroids [3, 5], oral retinoids [6], cyclosporine [6], combinations of intralesional and topical corticosteroids [7] and surgical intervention [5], have shown variable outcomes in the limited case reports available. While intralesional corticosteroids have been described in the literature for LPFT, they are typically used as part of combination therapy. In our case, we highlight the successful use of intralesional corticosteroids as a standalone treatment, with noticeable clinical improvement observed within two months of the initial injection. Due to the rarity of LPFT, evaluating the efficacy of treatment approaches remains challenging. Nonetheless, sharing diverse therapeutic strategies is essential to advancing understanding and guiding future management of this condition.

Conflicts of Interest

Dr. Prakash is a reviewer for Australasian Journal of Dermatology.

Data Availability Statement

The data that supports the findings of this study are available in the Supporting Information of this article.