Pseudolymphomatous folliculitis on the nose

Differential diagnoses of pseudolymphomatous folliculitis: considerations as regards one case

Pseudolymphomatous folliculitis (PLF) is a rare disease of cutaneous lymphoid hyperplasia, with a low index of clinical suspicion. We present the clinical case of a 19-year-old male patient, with a solitary violet erythematous nodule of 6 months of evolution, located in the right infraorbital region, without presenting another symptomatology. Histopathological examination showed a lymphocytic infiltrate that surrounds the hair follicles, sebaceous and sweat glands that focally destroy their basement membrane. PLF was diagnosed based on histological and immunohistochemical studies. In the multiple studies and case reports, the variability of the initial clinical diagnosis never corresponds to PLF, becoming a pathology with a low suspect index.

Lymphoma or pseudolymphoma: A report of six cases and review of the literature

To explore and compare the clinical presentations and pathologic features of cutaneous pseudolymphomas (CPL) with primary cutaneous lymphomas. Review literature in order to improve the treatment of CPL. Six cases of CPLs were collected. The clinical, pathologic, and immunohistochemical features were performed and analyzed in Peking Union Medical College Hospital in 2018. Of six patients, the distributions and clinical manifestations of skin lesions are varied. The pathologic features consisted of atypical prominent lymphocytes infiltration. Of them, two cases imitated mycosis fungoides, one case mimicked primary cutaneous aggressive pidermotropic CD8+ cytotoxic T-cell lymphoma, one case was diagnosed as Jessner-Kanof lymphocyte infiltration and two cases primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder. With respect to etiology, one was result from insects bite and the others were on account of drugs. All cases were treated with systemic or local glucocorticoid. The skin lesions and systemic symptoms showed notable improvement after treatment. Follow-up visits were 2 years, half a year, and months, respectively, without relapse. These unique types of CPL were similar to cutaneous lymphomas in clinical manifestation and pathology. They were all sensitive to the treatment of externally or orally using glucocorticoid. The prognosis is generally good but needs long-term follow-up.

Dermoscopy of Lymphomas and Pseudolymphomas

Primary cutaneous lymphomas are a heterogeneous group that includes 2 main groups of primary T- and B-cell lymphomas, which can involve the skin with distinct variability in clinical presentation, histopathology, immunophenotypes, molecular signature, and prognosis. The authors describe the most frequent clinical forms of cutaneous lymphomas and their dermoscopic features. Even if the diagnosis of these entities is still based on a cellular level and the literature on dermoscopy in cutaneous lymphomas is limited and, for several entities it is based only on single case reports/case series, we think that know how they appear also in dermoscopy can be useful for helping in the clinical diagnosis.

Red nodule on the face with "spontaneous" regression

Pseudolymphomatous folliculitis is a rare entity included among the cutaneous pseudolymphomas. A 32-year-old man, with an unremarkable medical history, presented with a two-month history of an asymptomatic solitary nodule on his left cheek. Histopathological examination demonstrated a dense nodular and diffuse dermal lymphocytic infiltrate with numerous histiocytes and dendritic cells that surrounded hypertrophic hair follicles. Pseudolymphomatous folliculitis commonly presents in the fourth decade of life, with no sex predominance, as an asymptomatic, rapidly growing and solitary red dome-shaped nodule on the face. It has a benign clinical course as the lesions usually resolve with surgical excision or regress spontaneously after incisional biopsy. Although there is no report of pseudolymphomatous folliculitis progressing into lymphoma in the literature, follow-up of these patients is recommended.

Cutaneous Pseudolymphomas

The term cutaneous pseudolymphoma refers to benign reactive lymphoid proliferations in the skin that simulate cutaneous lymphomas. It is a purely descriptive term that encompasses various reactive conditions with a varied etiology, pathogenesis, clinical presentation, histology, and behavior. We present a review of the different types of cutaneous pseudolymphoma. To reach a correct diagnosis, it is necessary to contrast clinical, histologic, immunophenotypic, and molecular findings. Even with these data, in some cases only the clinical course will confirm the diagnosis, making follow-up essential.

PD-1, S-100 and CD1a expression in pseudolymphomatous folliculitis, primary cutaneous marginal zone B-cell lymphoma (MALT lymphoma) and cutaneous lymphoid hyperplasia

BACKGROUND

Pseudolymphomatous folliculitis is a lymphoid proliferation that clinically and histopathologically mimics primary cutaneous extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma). In this study, we assessed the diagnostic value of three immunohistochemical markers, programmed death-1 (PD-1), CD1a and S100.

METHODS

We evaluated 25 cases of cutaneous lymphoid proliferations with established diagnoses, including 9 patients with pseudolymphomatous folliculitis, 11 with MALT lymphoma, and 5 with cutaneous lymphoid hyperplasia (CLH). The clinical, histopathologic and immunohistochemical characteristics were reviewed and three major characteristics assessed: (a) proportion of T cells expressing PD-1, (b) pattern of expression of CD1a by dendritic cells and (c) pattern of expression of S100 by dendritic cells.

RESULTS

We found pseudolymphomatous folliculitis to have a significant increase in PD-1+ T cells compared with MALT lymphoma (p < 0.0001). The pattern of CD1a staining is also informative: MALT lymphoma is significantly more likely to demonstrate a peripheral concentration of CD1a+ dendritic cells around lymphoid nodules than pseudolymphomatous folliculitis (p < 0.0003) or CLH (p < 0.05). Pseudolymphomatous folliculitis demonstrates an interstitial distribution of CD1a+ cells more often than MALT lymphoma (p < 0.04). S100 staining was not a helpful discriminator.

CONCLUSIONS

Histopathologic factors including PD-1 and CD1a staining patterns may allow for more certainty in distinguishing lymphoid hyperplasia, including pseudolymphomatous folliculitis, from MALT lymphoma.

Pseudolymphomatous folliculitis: a distinctive cutaneous lymphoid hyperplasia

Pseudolymphomatous folliculitis (PLF) was first described in 1986 as a distinct variant of pseudolymphoma, characterized by a dense lymphoid infiltrate and accompanied by hyperplastic hair follicles. Here in we report a case of PLF presenting as an erythematous plaque with pustules and satellite lesions on forehead in an otherwise healthy adult male patient.

Dermoscopy findings of pseudolymphomatous folliculitis

Pseudolymphomatous folliculitis (PLF), which clinically mimicks cutaneous lymphoma, is a rare manifestation of cutaneous pseudolymphoma and cutaneous lymphoid hyperplasia. Here, we report on a 45-year-old Japanese woman with PLF. Dermoscopy findings revealed prominent arborizing vessels with small perifollicular and follicular yellowish spots and follicular red dots. A biopsy specimen also revealed dense lymphocytes, especially CD1a+ cells, infiltrated around the hair follicles. Without any additional treatment, the patient's nodule rapidly decreased. The presented case suggests that typical dermoscopy findings could be a possible supportive tool for the diagnosis of PLF.