Pseudolymphomatous Folliculitis Research Articles

Pseudolymphomatous folliculitis presenting as an eruptive nodule over the mandibular area.

Pseudolymphomatous folliculitis presenting as an eruptive nodule over the mandibular area.

Distribution of CD1a-positive cells is not different between pseudolymphomatous folliculitis and primary cutaneous marginal zone lymphoma.

Pseudolymphomatous folliculitis (PLF) is a subtype of cutaneous pseudolymphoma that is recognized as an independent disease. PLF is characterized by dermal lymphocytic infiltration surrounding an irregular hyperplastic pilosebaceous unit (i.e., activated pilosebaceous unit). An interstitial distribution of CD1a-positive cells is regarded as an important feature of PLF, especially in distinguishing it from primary cutaneous marginal zone lymphoma (PCMZL), which is associated with a peripheral concentration of CD1a-positive cells. We undertook a clinicopathological investigation of PLF, with a reassessment of CD1a immunohistochemistry. We defined diagnostic criteria for PLF based on past studies and consequently identified 79 cases. In addition, we collected 32 cases of PCMZL and performed detailed clinical, pathological, and immunohistochemical investigations using antibodies to CD3, CD20, and CD1a. We found an interstitial concentration of CD1a-positive cells in 90.2% of PLF and 34.5% of PCMZL cases. The peripheral concentration of CD1a-positive cells was seen in 9.8% of PLF and 34.5% of PCMZL cases. In both diseases, CD1a-positive cells appeared in T-cell nests (88.5% in PLF and 92.9% in PCMZL) but were absent in B-cell nests (0% in both groups). All 79 cases of PLF showed activated pilosebaceous units while 22 of the 32 PCMZL cases displayed pilosebaceous units, although none of these were activated. In summary, regarding the distribution patterns of CD1a-positive cells as a diagnostic feature in distinguishing between PLF and PCMZL is somewhat inconclusive. To differentiate PLF and PCMZL, determining the presence or absence of activated pilosebaceous units is essential.

Differential NFATc1 Expression in Primary Cutaneous CD4+ Small/Medium-Sized Pleomorphic T-Cell Lymphoma and Other Forms of Cutaneous T-Cell Lymphoma and Pseudolymphoma.

Primary cutaneous CD4 small/medium-sized pleomorphic T-cell lymphoma (PCSTCL) has recently emerged as a distinct clinicopathological entity. Because of a considerable degree of overlap with pseudolymphoma, the diagnosis is often challenging. Preliminary studies suggest that nuclear upregulation of calcineurin/nuclear factor of activated T cells (NFAT) may play a role in lymphomagenesis. 137 cases (70 males and 67 female, mean age = 55) of various forms of cutaneous T-cell and B-cell infiltration were evaluated for NFATc1 expression. The study comprised 18 cases of PCSTCL, 45 cases of mycosis fungoides (MF), 5 cases of lymphomatoid papulosis (LyP), 5 cases of anaplastic large-cell lymphoma (ALCL), 8 cases of other forms of peripheral T-cell lymphoma, not otherwise specified, 12 precursor lesions of MF (ie, cutaneous T-cell dyscrasias), 35 cases of pseudolymphomas, 8 primary cutaneous B-cell lymphoma, and 1 chronic lymphocytic leukemia. The number of cells exhibiting a nuclear stain was counted per 10 high-power field and 2-tailed statistical analysis was used for comparison of nuclear NFATc1 expression between primary PCSTCL and all other groups. A P-value <0.05 was considered to indicate statistical significance. All cases of PCSTCL showed nuclear staining for NFATc1 (mean = 296 ± 236) with no cases in which an exclusive cytoplasmic stain was observed. The cells exhibiting this staining pattern were oftentimes larger manifesting other features of a follicular helper T-cell phenotype, such as variable positivity for PD1, ICOS, CXCL13, and BCL6. In comparison, an exclusively cytoplasmic stain was observed in 29 cases of MF; in few cases, rare nuclear staining cells were observed averaging less than 10 per high-power field (P = 0.0001). These positive staining cases were not only limited to tumor-stage MF but also encompassed patch- and plaque-stage lesions and follicular variants of MF. The same pattern was observed in cases of T-cell dyscrasia (mean = 3 ± 3, P = 0.0001) and pseudolymphoma (mean = 2 ± 3, P = 0.0001), both revealing a dominant cytoplasmic staining pattern. In pseudolymphomatous folliculitis, a greater extent of nuclear staining for NFATc1 was observed compared with other forms of pseudolymphoma. No significant difference was seen between MF and T-cell dyscrasia or pesudolymphomas excluding pseudolymphotous folliculitis. Anaplastic large-cell lymphoma cases showed an almost exclusive cytoplasmic staining pattern with rare nuclear staining (mean = 55 ± 102, P = 0.0001); similar results were observed in LyP (mean = 17 ± 15, P = 0.004). Cutaneous B-cell lymphomas showed a similar extent of staining as that noted for PCSTCL. The greatest extent of staining was observed in chronic lymphocytic leukemia. A significant difference was noted between the extent of nuclear staining in PCSTCL and other forms of primary cutaneous T-cell lymphoma, type unspecified (mean = 22 ± 43, P = 0.0002), although not between PCSTCL and B-cell lymphoma. NFAT signaling plays a critical role in peripheral T-cell activation after T cell receptor engagement. When assessing T-cell-rich infiltrates where the differential diagnosis is largely between a PCSTCL and pseudolymphoma, a significant degree of nuclear staining of lymphocytes would be more in keeping with a diagnosis of PCSTCL. Upregulation of the NFAT pathway is not a feature of tumor progression in the setting of MF.

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

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. 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. 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. 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.

A case of recurrent pseudolymphomatous folliculitis: A mimic of cutaneous lymphoma

Pseudolymphomatous folliculitis is a rare entity. We present a 62-year-old man with a recurrent solitary nodule on his nose requiring multiple excisions. Microscopic examination of the excisions showed a dense lymphocytic infiltrate containing numerous histiocytes and S100+, CD1a+ dendritic cells that surrounded and infiltrated hypertrophic hair follicles. Diffuse sheets of CD3+ T cells and nodular clusters of CD20+ B cells were also seen. There was normal reactive pattern of follicular centers. Light chain restriction was not detected. T-cell receptor and immunoglobulin heavy chain gene rearrangements by polymerase chain reaction revealed negative findings. A diagnosis of pseudolymphomatous folliculitis was made based on the hypertrophic hair follicles, periadnexal S100+ and CD1a+ dendritic cells, and negative clonal gene rearrangement study findings. This case of recurrent pseudolymphomatous folliculitis is instructive because of the resemblance to cutaneous lymphomas and cutaneous lymphoid hyperplasias, and the need for correct diagnosis to avoid overtreatment of this indolent condition.

Pseudolymphomatous folliculitis presenting with multiple nodules

Auteur(s) : Motonobu Nakamura, Kenji Kabashima, Yoshiki Tokura Department of Dermatology, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan Pseudolymphomatous folliculitis (PLF) was first described in 1986 as a distinct variant of pseudolymphoma, characterized by a dense lymphoid infiltrate accompanied by hyperplastic hair follicles [1]. Clinically, PLF is typified by a solitary dome-shaped or flat-elevated nodule, [...]

Hyperplasia of Hair Follicles and Other Adnexal Structures in Cutaneous Lymphoproliferative Disorders

We studied 53 cutaneous lymphoproliferative disorders, all of which manifested hair follicle hyperplasia. There were 42 cases conforming to the description of pseudolymphomatous folliculitis (PLF) and 11 cases of authentic lymphomas including mycosis fungoides, CD30+ anaplastic large cell lymphoma, diffuse large B-cell lymphoma, B-cell small cell lymphoma/leukemia, and peripheral T-cell lymphoma, not otherwise specified. All patients with PLF clinically presented with a solitary nodule preferentially involving the face. Beside hair follicle hyperplasia, the typical features were a dense infiltrate of small well-differentiated lymphocytes, lymphoplasmacytoid cells, plasma cells, and epithelioid histiocytes forming tiny granulomas. Some unusual or worrisome features recognized included eccrine/apocrine duct hyperplasia, subcutis/muscle infiltration, lymphocyte "smudging," single file infiltration, and large atypical cells. Immunohistochemically, T-cell predominant cases dominated in the series. All 34 tested cases revealed a polyclonal pattern of kappa and lambda immunoglobulin (Ig) light chain expression. In 4 cases, scattered CD30+ cells were identified. Monoclonal rearrangements of T-cell receptor (TCR) and IgH genes were detected in 19 and 3 cases respectively, including 1 case with dual T-cell receptor/IgH rearrangement. Three of 30 tested cases proved positive for herpes simplex virus-1, whereas herpes simplex virus-2 always tested negative. Of 31 cases tested for Borrelia burgdorferi, 30 specimens were negative. In 9 cases, fluorescent in situ hybridization for t(11;18) and t(14;18) revealed none of the above translocations. The most common treatment modality was surgical removal. Forty patients with a mean follow-up of 3.7 years included 39 patients with no evidence of disease and 1 individual with local recurrence. The comparison of "clonal cases of PLF" and those with polyclonal population or in which clonality remained undetermined revealed no differences between the 2 groups in the clinical presentation, pathologic, and immunohistochemical features. We conclude that hyperplasia of hair follicles and other adnexa can be seen not only in the condition currently known as PLF, but also in genuine cutaneous lymphomas and may be just a happenstance secondary to a basic pathologic process.

Folliculite pseudolymphomateuse du visage chez un enfant : aspect hypochromique

The entity called pseudolymphomatous folliculitis (PLF) is a cutaneous pseudolymphoma. We report a new case of PLF with an atypical clinical presentation. A 6-year-old child was examined for an asymptomatic, hypochromic lesion of the face progressing for three months. The histology showed the activated pilosebaceous units with characteristic perifollicular infiltration by T-cells associated with dendritic cells expressing CD1a and protein S100. The outcome was spontaneously favourable. All of the foregoing elements supported a diagnosis of PLF. PLF is defined as a clinical-pathological entity among the cutaneous pseudolymphomas. The usual clinical aspect is that of a solitary red-to-violaceous asymptomatic nodule measuring less than 1.5cm in diameter. Histology shows follicular invasion characterized by lymphocytic infiltration into pilosebaceous units, creating architectural distortion; this infiltration is associated to perifollicular dendritic cells expressing CD1a and protein S100. We report this new case of PLF because of its peculiar clinical presentation. However, FPL remains a controversial entity, since the follicular location of the pseudolymphomatous lymphocytic infiltration seems poorly specific in facial lesions.

Clinicopathologic Study of Cutaneous Pseudolymphomas

A study was conducted to determine the clinical and histopathologic findings of cutaneous pseudolymphomas. In the period between July of 1989 and December of 2002, 42 cases were collected. Clinical records and pathology slides of the patients were reviewed retrospectively. A striking common clinical feature was a pruritic papule, nodule, or plaque with a smooth surface on the head and neck. The histologic patterns were diverse, MF-like, perivascular/periadnexal, nodular, diffuse, pseudolymphomatous folliculitis, and acral pseudolymphomatous angiokeratoma of children (APACHE) patterns. The most common pattern was a multinodular pattern with an extension into the deep dermis and subcutaneous adipose tissue. The differentiation between cutaneous lymphomas and pseudolymphomas must depend on a constellation of criteria, never on a single criterion.

A review of 55 cases of cutaneous lymphoid hyperplasia: reassessment of the histopathologic findings leading to reclassification of 4 lesions as cutaneous marginal zone lymphoma and 19 as pseudolymphomatous folliculitis

To clarify the confusion surrounding the diagnosis of cutaneous lymphoid hyperplasia (CLH) that was formerly described as lymphadenosis benigna cutis, lymphocytoma cutis, or lymphocytic infiltration of Jessner and to assess whether newly recognized diagnoses, such as cutaneous marginal zone lymphoma and pseudolymphomatous folliculitis (PLF), may have been overlooked, we reexamined 55 Japanese cases of nonepidermotropic lymphoproliferative disorder that had previously been diagnosed as "cutaneous pseudolymphoma." In all these cases, the immunohistochemical expressions of CD1a, CD3, CD4, CD8, CD20, CD21, CD30, CD43, CD56, CD68, CD79a, kappa and lambda chains, S-100 protein, and latent membrane protein were assessed. In addition, in 13 cases the gene rearrangement of the immunoglobulin heavy chain was investigated using a polymerase chain reaction method. As a result of these investigations, we have identified 4 cases of cutaneous marginal zone lymphoma, 19 cases of PLF, 1 case of diffuse large B-cell lymphoma, and 2 cases of solitary nonepidermotropic pseudo-T-cell lymphoma, with the remaining 29 cases being CLH. Cutaneous marginal zone lymphoma, which represented 7.3% of the total, was distinguished from CLH by the presence of patchy or diffuse proliferation of centrocyte-like cells, plasma cells at the periphery of the lymphocytic infiltration, monotypic restriction of the light chains, and gene rearrangement of the immunoglobulin heavy chain. Pseudolymphomatous folliculitis was identified by the presence of activated pilosebaceous units with abundant CD1a-and S-100 protein-positive T-cell-activated dendritic cells. Of the cases that were reassessed, 34.5% were PLF.

Pseudolymphomatous folliculitis: a clinicopathologic study of 15 cases of cutaneous pseudolymphoma with follicular invasion.

We report the clinical, histopathologic, and immunohistologic features of 15 cases of pseudolymphomatous folliculitis (PLF). The patients comprised seven males and eight females (mean age, 38.6 years; age range, 2-67 years). All patients had dome-shaped or flat-elevated nodules suggestive of cutaneous lymphoid hyperplasias (CLHs). The lesions were solitary in all 15 cases, except in one case with duplex lesions. All lesions were located on the face and measured less than 1.5 cm. In 14 cases with one lesion each, five lesions showed rapid regression after incisional biopsy, whereas the remaining nine underwent excisional biopsy. In the case with duplex lesions, one regressed spontaneously after excisional biopsy of the other. Histopathologically, all PLFs showed dense lymphocytic infiltrates from the dermis to the subcutis simulating cutaneous lymphomas. The walls of hair follicles in all cases were enlarged and irregularly deformed with their epithelium blurred by lymphocytic infiltrates; we called this change "activation" of hair follicles. In nine cases, many atypical lymphocytes were intermingled; three of these cases had been misdiagnosed as cutaneous T-cell lymphoma at other institutions. Immunohistologically, 10 and 5 cases showed predominantly B cells and predominantly T cells, respectively. Remarkably, all lesions showed increased numbers of perifollicular histiocytes expressing anti-S-100 protein and CD1a, and seven lesions showed histiocytes in aggregates. We conclude that PLF is a subset of CLH with characteristic clinical and pathologic features showing perifollicular clustering of T-cell-associated dendritic cells with activation of pilosebaceous units. PLF is an entity to be differentiated from malignant lymphomas and other cutaneous pseudolymphomas.