Pseudolymphomatous Folliculitis Presenting as Multiple Facial Papules: A Diagnostic and Therapeutic Challenge

Dear Editor, Pseudolymphomatous folliculitis (PLF) is a rare variant of cutaneous pseudolymphoma characterized by dense lymphoid infiltration of hair follicles. Although most reported cases involve solitary lesions, we report a patient with multiple papules on the face and neck, an uncommon presentation that can mimic cutaneous lymphoma and poses a diagnostic challenge, particularly in resource-limited settings. A 24-year-old woman presented with a two-year history of recurrent, erythematous, mildly pruritic papules on the face and neck. She had been intermittently treated with various topical preparations without sustained improvement. There was no history of systemic symptoms, photosensitivity, trauma, insect bite, or cosmetic exposure. Personal and family histories were unremarkable. Clinical examination revealed multiple erythematous to skin-colored papules on the cheeks, chin, and lateral neck [Figure 1a, 1b]. No pustules, comedones, or mucosal lesions were observed. Regional lymph nodes were not enlarged. Routine hematological and biochemical investigations were within normal limits. Dermoscopy could not be performed initially because of unavailability of the device, and the patient was later lost to follow-up.Figure 1: (a): Multiple erythematous to skin-colored papules on the right cheek, chin, and neck. (b): Multiple erythematous to skin-colored papules on the forehead, left cheek, and chinHistopathology of a punch biopsy from the left cheek revealed a dense, deep dermal lymphocytic infiltrate with prominent perifollicular and folliculotropic distribution, partial follicular destruction, and the absence of follicular mucinosis or epidermotropism. Scattered histiocytes were present without cytologic atypia, necrosis, or granuloma formation [Figures 2 and 3]. No bacterial or fungal elements were identified on special stains.Figure 2: Dense dermal lymphocytic infiltrate prominent perifollicular and folliculotropic distribution and partial follicular disruption (Hematoxylin and eosin, 40×)Figure 3: Dense dermal lymphocytic infiltrate with a few histiocytes (Hematoxylin and eosin, 400×)Immunohistochemistry (IHC) demonstrated a mixed polyclonal infiltrate composed of CD3+ T cells and CD20+ B cells, with preserved CD5 and CD7 expression and no κ/λ light-chain restriction. CD30 and CD23 were negative, ruling out cutaneous T- or B-cell lymphoma. Molecular clonality studies (T-cell receptor or immunoglobulin heavy-chain gene rearrangement) could not be performed due to resource constraints. However, clinicopathologic correlation and the polyclonal IHC pattern were diagnostic of PLF. PLF is an uncommon subtype of cutaneous pseudolymphoma characterized by folliculotropic lymphoid infiltrates that can closely resemble cutaneous lymphomas both clinically and histologically. The importance of accurate diagnosis lies in avoiding overtreatment and unnecessary anxiety. The various clinical diagnoses considered are summarized in Table 1.Table 1: Clinical differential diagnoses consideredPLF is classically solitary. In Arai et al.’s[1] clinicopathologic series of 15 cases, lesions were solitary in all but one patient who had duplex lesions. Nonetheless, rare multifocal or multiple-lesion presentations have been described, including Nakamura et al. reporting multiple nodules, Horikiri et al. describing multiple large firm violaceous nodules on the cheek, and a small series by Granados-López et al. noting one case with multiple lesions.[2-4] Taken together, published reports suggest only a handful of multifocal PLF cases to date, underscoring the rarity of this presentation. Our case contributes to this limited body of literature and highlights the diagnostic challenge of distinguishing multifocal PLF from cutaneous lymphoma, especially in resource-limited settings. The etiopathogenesis of PLF remains uncertain. It is thought to represent a reactive lymphoid hyperplasia triggered by chronic antigenic stimulation such as arthropod bites, trauma, or infections.[5] No identifiable trigger was found in our patient. Histopathologically, PLF exhibits two principal patterns: (a) follicular destruction by the infiltrate and (b) follicular hyperplasia with distorted outlines.[1] The present case corresponded to the destructive type, showing partial follicular disruption. The absence of cytologic atypia, necrosis, and epidermotropism helps to differentiate PLF from lymphomas and granulomatous dermatoses. IHC is indispensable for differentiating PLF from cutaneous lymphomas. PLF typically demonstrates a polyclonal population of CD3+ T cells and CD20+ B cells with preserved pan-T-cell markers and no light-chain restriction.[1,4] In contrast, lymphomas display monoclonality or aberrant marker expression. The immunophenotype in our case confirmed polyclonality and excluded malignancy. There are no standardized treatment guidelines for PLF. Solitary lesions are often managed by surgical excision, which is both diagnostic and therapeutic.[5] For multifocal or persistent disease, therapies such as topical or intralesional corticosteroids, doxycycline, hydroxychloroquine, or low-dose methotrexate have been used.[2-5] Our patient showed partial improvement with doxycycline, chosen for its anti-inflammatory and immunomodulatory effects. Low-dose methotrexate was considered, but the patient was lost to follow-up. The prognosis of PLF is excellent, with no documented risk of malignant transformation or systemic spread. Some cases undergo spontaneous regression. Nonetheless, long-term follow-up is advised to monitor for recurrence or changes suggesting an alternative diagnosis. In conclusion, this case highlights an unusual multifocal presentation of PLF, a benign but diagnostically challenging entity that can closely simulate cutaneous lymphoma. Recognition of its clinicopathologic features and confirmation of polyclonality on IHC are crucial to prevent misdiagnosis and unnecessary aggressive therapy, particularly in resource -constrained settings. Authors’ contributions We confirm that all authors have read and approved the manuscript for submission. All authors meet authorship criteria, and the manuscript represents honest work. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Use of artificial intelligence (AI) The preparation of this manuscript was carried out entirely by the authors without the use of artificial intelligence technologies.