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Mycosis fungoides with large cell transformation (MFLCT) can be difficult to distinguish from primary cutaneous CD30+ T cell lymphoproliferative disorders (PC CD30+ LPD), especially primary cutaneous anaplastic large cell lymphoma (PC-ALCL). This diagnostic distinction is critical for appropriate patient management. GATA3 has been proposed to be useful in the discrimination between these two entities. We identified 25 cases of MFLCT and 24 cases of PC CD30+ LPDs (including lymphomatoid papulosis (n=14), PC-ALCL (n=6), and CD30+ LPD, not otherwise specified (n=4)) diagnosed at our institution from 2002 to 2019. Sections from archived specimens were stained to evaluate for GATA3 expression by immunohistochemistry and compared among cutaneous CD30+ T cell LPDs. The majority of the MFLCT cohort had strong, diffuse expression of GATA3 ranging from 0 to 100% of dermal T cells (mean 53.20%) with 15/25 cases (60%) showing GATA3 expression greater than 50%, while the PC CD30+ LPD group showed variable, moderate GATA3 labeling ranging from 0 to 60% of dermal T cells (mean 23.26%), with 5/6 cases (83%) showing GATA3 expression less than 40% (p =0.003). The calculated sensitivity and specificity were 56% and 74%, while positive and negative predictive values were 70% and 61%, respectively. Based on the percent staining of positive cells, using 50% as a cutoff value for expression, GATA3 might be a useful immunohistochemical marker to discriminate MFLCT from PC CD30+ LPDs, including PC-ALCL., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.)

Acral lymphomatoid papulosis (a-LyP) is a rare clinical variant of LyP whose diagnosis may be challenging. A case series of a-LyP was studied clinically, histopathologically, immunohistochemically, and from molecular point of view. Including ours, 25 cases of a-LyP have so far been reported. Clinically, a-LyP may present as acral involvement exclusively, in combination with mucosal lesions, (in itself a rare presentation), or in association with conventional LyP. The age of presentation was slightly higher than that of conventional LyP (55 vs 45 years) and a male predominance has been observed, as usually reported. Histopathologically, no morphological differences exclusively from conventional LyP were observed. LyP types A and E were the main variants. We describe for the first time one case of type D a-LyP. Acral LyP is a rare entity and correct diagnosis can only be reached with clinical and histopathological correlation, to avoid aggressive treatment of this indolent lymphoproliferative disorder., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

We present the case of an ulcerative lesion of the eyelid as first presentation of type A lymphomatoid papulosis (LP) in a young adult. LP is a rare cutaneous lymphoproliferative disease with a risk of associated systemic or cutaneous lymphoma.

We report on a 73-year-old male patient with recurrent thrombosis of his infrarenal aortic prosthesis. Histologically, the thrombus contained cells of an ALK-negative anaplastic large cell T cell lymphoma (ALCL). Imaging studies were negative for other lymphoma manifestations; however, 3 months before, the patient had developed skin lesions consistent with lymphomatoid papulosis type A (LypA) which were clonally related to the ALCL. Due to recurrent thrombosis of larger peripheral arteries with the presence of ALCL cells in the thrombi, the patient is now referred to systemic chemotherapy. We present the first case of ALCL manifesting in the thrombus of an aortic prosthesis. This case shows similarities to the well-established entity of breast implant-associated ALCL and anecdotal reports of ALCL occurring at the site of foreign material implants. These cells show a peculiar propensity to aggregate in vessels and thrombi, known primarily from subtypes of diffuse large B cell lymphomas associated with chronic inflammation.

The histopathological characteristics of lymphomatoid papulosis (LyP) vary. Currently, 6 subtypes have been reported, including a new subtype with perifollicular infiltration and different degrees of folliculotropism of CD30+ atypical lymphocytes, known as follicular LyP. However, LyP pathologically manifesting with folliculotropism, eccrinotropism and neurotropism has been rarely reported. We present a case of LyP showing CD30+ atypical lymphocytes around the hair follicle, eccrine gland and nerve fiber, with varying degrees of infiltrates. The pathological characteristics of folliculotropism and eccrinotropism are often associated with mycosis fungoides (MF). This case suggests that differential diagnosis is necessary when atypical lymphocytes infiltrate the follicle and eccrine gland. As folliculotropism and eccrinotropism can occur in both MF and LyP, it may represent a conceptual intersection between the 2 disease processes., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Lymphomatoid papulosis (LyP), characterized by recurring, waxing and waning, cutaneous papulonodules, is increasingly recognized to represent a heterogeneous collection of pathologically dissimilar subtypes. Recently, a follicular LyP variant was proposed, featuring folliculotropism. Folliculotropism by atypical lymphocytes is conventionally associated with follicular mucinosis and mycosis fungoides (MF), and review of the literature suggests co-occurrence of folliculotropism and follicular mucinosis in LyP to be rare, with only 3 cases identified to date. Herein we describe 3 additional cases, each manifesting a typical LyP clinical picture, with the additional element of folliculotropism and follicular mucinosis on pathology. These cases suggest that LyP should be considered alongside MF in the differential diagnosis of follicular mucinosis with accompanying atypical lymphocytic infiltration. As LyP can occur with other lymphoproliferative disorders such as MF, the finding of follicular mucinosis in LyP may further represent a conceptual intersection between the 2 disease processes., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Primary cutaneous CD30 + lymphoproliferative disorders encompass lymphomatoid papulosis (LyP), primary cutaneous anaplastic large cell lymphoma (pcALCL), and indeterminate cases. LyP is a benign disorder characterized by recurrent crops of red or violaceous papulonodules. Patients with LyP are at an increased risk of a secondary malignancy. pcALCL is characterized by a solitary red to violaceous nodule or tumor larger than 20 mm. LyP is benign, is limited to the skin, and self-resolves, with a 5-year survival rate of 100%; pcALCL is limited to the skin and responsive to directed therapies, with a 5-year survival rate of over 95%. Aggressive chemotherapeutic regimens should be avoided., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Lymphomatoid papulosis (LyP) belongs to the group of cutaneous CD30+ lymphoproliferative disorders. Pseudocarcinomatous hyperplasia has rarely been reported in patients with LyP. In this report, we describe a case of LyP presenting as pseudocarcinomatous hyperplasia. The patient was a 7-year-old girl who presented with a recurrent papulonodular eruption on her face and trunk for 2 months. Histopathologic examination revealed an irregular growth of hyperkeratotic epidermis into the whole dermal layer with marked nests of squamous cells in the background of diffuse atypical lymphoid cells, eosinophils and neutrophils. The large atypical cells were positive for CD30 and CD3, but negative for CD4, CD5, CD8, CD20 and CD56. A TCR-γ clone was identified by polymerase chain reaction (PCR). The correct diagnosis in cases of LyP with overlying pseudocarcinomatous epithelial hyperplasia can be very difficult both clinically and histopathologically. Clinical and histopathologic characteristics should be integrated to avoid an erroneous diagnosis of squamous cell carcinoma or keratoacanthoma., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Mycosis fungoides (MF) is the most common primary cutaneous T-cell lymphoma (CTCL), followed by CD30+ lymphoproliferative disorders, including lymphomatoid papulosis (LyP) and primary cutaneous anaplastic large cell lymphoma (pcALCL). The objective was to report on a series of patients with different types of CTCL at different times in their clinical course, with a focus on clonality studies., Methods: Four patients with multiple diagnoses of CTCLs were identified. The clinical information, treatment interventions, and histopathology were reviewed. T-cell receptor (TCR) gene rearrangement studies were performed on all available specimens., Results: The four patients carried diagnoses of: (1) pcALCL and MF; (2) pcALCL, LyP, and pcALCL; (3) LyP, MF, and pcALCL; (4) LyP, pcALCL, and MF; each with characteristic presentation and histopathologic findings. The results of the TCR polymerase chain reaction showed that all tumors expressed and retained a TCR clone(s) as follows: (1) biallelic clone; (2) single clone; (3) biallelic clone with additional clone; and (4) single clone, respectively., Conclusion: We report a series of four cases of individual patients with coexisting diagnoses of some combination of MF, LyP, and pcALCL, whose lesions presented in nontraditional sequence and demonstrated a retained clone by gene rearrangement analysis., (© 2015 The International Society of Dermatology.)

Lymphomatoid papulosis (LyP) is an uncommon CD30 lymphoproliferative disorder with a relatively excellent prognosis. Ten to twenty percent of cases, however, are associated with a lymphoma, typically systemic or cutaneous anaplastic large cell lymphoma, mycosis fungoides, or Hodgkin lymphoma. Subtypes divide LyP into infiltrate-descriptive categories along a spectrum of histological manifestation. Classically, LyP shows a patchy, wedge-shaped, perivascular dermal infiltrate of small- to intermediate-sized lymphoid cells, larger lymphoid, with one, 2, or multiple prominent nucleoli, and a variable admixture of neutrophils, eosinophils, and histiocytes. Follicular LyP shares these characteristics, although its infiltrate is folliculocentric. Variable folliculotropism, follicular dilation, rupture, and mucinosis can occur. This entity is commonly misdiagnosed and underreporting likely because its histopathologic features can masquerade as more common follicular-based entities. The authors present 2 cases of this rare variant to underscore the importance of clinicopathologic correlation in diagnosis. To the best of the authors' knowledge, this is the first report of the follicular LyP variant with concurrent mycosis fungoides. In the context of a literature review, diagnostic pitfalls and classification of this variant are discussed.

Pseudocarcinomatous hyperplasia can occasionally be observed in biopsies of CD30-positive lymphoproliferative disorders. It is important to be cognizant of this association, because epithelial hyperproliferation can overshadow large atypical lymphoid cells, leading to an erroneous diagnosis of squamous cell carcinoma (SCC) or keratoacanthoma. Herein, we present a case of anaplastic large cell lymphoma (ALCL) with pseudocarcinomatous hyperplasia simulating a poorly differentiated carcinoma and review the literature on this subject. Immunohistochemical staining with p63 helped delineate the infiltrating tongues of pseudocarcinomatous hyperplasia from the malignant infiltrate. We present this case to raise awareness of the potential for pseudocarcinomatous hyperplasia to occur in the setting of CD30+ lymphoproliferative disorders. Clinicians and dermatopathologists should consider the possibility of ALCL or lymphomatoid papulosis when examining lesions with features of inflamed SCC, especially if the tumor presents on a site or in a patient that is not typical of SCC., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

MicroRNAs usually regulate gene expression negatively, and aberrant expression has been involved in the development of several types of cancers. Microarray profiling of microRNA expression was performed to define a microRNA signature in a series of mycosis fungoides tumor stage (MFt, n=21) and CD30+ primary cutaneous anaplastic large cell lymphoma (CD30+ cALCL, n=11) samples in comparison with inflammatory dermatoses (ID, n=5). Supervised clustering confirmed a distinctive microRNA profile for cutaneous T-cell lymphoma (CTCL) with respect to ID. A 40 microRNA signature was found in MFt including upregulated onco-microRNAs (miR-146a, miR-142-3p/5p, miR-21, miR-181a/b, and miR-155) and downregulated tumor-suppressor microRNAs (miR-200ab/429 cluster, miR-10b, miR-193b, miR-141/200c, and miR-23b/27b). Regarding CD30+ cALCL, 39 differentially expressed microRNAs were identified. Particularly, overexpression of miR-155, miR-21, or miR-142-3p/5p and downregulation of the miR-141/200c clusters were observed. DNA methylation in microRNA gene promoters, as expression regulatory mechanism for deregulated microRNAs, was analyzed using Infinium 450K array and approximately one-third of the differentially expressed microRNAs showed significant DNA methylation differences. Two different microRNA methylation signatures for MFt and CD30+ cALCL were found. Correlation analysis showed an inverse relationship for microRNA promoter methylation and microRNA expression. These results reveal a subgroup-specific epigenetically regulated microRNA signatures for MFt and CD30+ cALCL patients.

Background: In nodal anaplastic large cell lymphoma, strong expression of galectin-3 (Gal-3) has been found, but only very few cases of primary cutaneous lymphoma have so far been examined., Objectives: To investigate 11 primary cutaneous anaplastic large cell lymphomas (PCALCL), 47 lymphomatoid papuloses (LYP) and 14 cases of transformed mycosis fungoides with CD30 expression (MF-T) for Gal-3 expression., Methods: A Gal-3 score was applied using a photo-based morphometric evaluation program. Double staining for CD30 and Gal-3 was performed. Furthermore, we recorded the cellular and extracellular sublocalization of the signal., Results: The Gal-3 expression in CD30+ tumor cells was significantly lower in MF-T in contrast to CD30+ lymphoproliferative disorders (CD30 LPD; p < 0.001), but we found no differences between PCALCL and LYP (p = 0.42). In PCALCL Gal-3 was more often localized in the cytoplasm in contrast to LYP, in which an equal distribution in the cytoplasm and the nucleus was more common (p = 0.9)., Conclusions: The lower Gal-3 expression in MF-T in comparison to CD30 LPD might be an additional criterion to differentiate both entities. The different sublocalization of the Gal-3 signal might reflect a different biological function and behavior.

The spectrum of cutaneous CD30-positive lymphoproliferative disorders (LPDs) includes lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Chromosomal translocations targeting tyrosine kinases in CD30-positive LPDs have not been described. Using whole-transcriptome sequencing, we identified a chimeric fusion involving NPM1 (5q35) and TYK2 (19p13) that encodes an NPM1-TYK2 protein containing the oligomerization domain of NPM1 and an intact catalytic domain in TYK2. Fluorescence in situ hybridization revealed NPM1-TYK2 fusions in 2 of 47 (4%) primary cases of CD30-positive LPDs and was absent in other mature T-cell neoplasms (n = 151). Functionally, NPM1-TYK2 induced constitutive TYK2, signal transducer and activator of transcription 1 (STAT1), STAT3, and STAT5 activation. Conversely, a kinase-defective NPM1-TYK2 mutant abrogated STAT1/3/5 signaling. Finally, short hairpin RNA-mediated silencing of TYK2 abrogated lymphoma cell growth. This is the first report of recurrent translocations involving TYK2, and it highlights the novel therapeutic opportunities in the treatment of CD30-positive LPDs with TYK2 translocations., (© 2014 by The American Society of Hematology.)

Background: The methylation of DNA at position 5 of cytosine, and the subsequent reduction in intracellular 5-hydroxymethylcytosine (5-hmC) levels, is a key epigenetic event in several cancers, including systemic lymphomas. However, no studies have analyzed this epigenetic marker in cutaneous lymphomas. Therefore, we aimed to analyze the expression of 5-hmC in cutaneous CD30-positive lymphoproliferative disorders and compare it with a control group composed of reactive infectious and inflammatory disorders with CD30-positive cells., Methods: Retrospective case series study with immunohistochemical analysis using anti-CD30 and anti-5-hmC antibodies in control (n = 19), lymphomatoid papulosis (LyP) (n = 27) and primary cutaneous anaplastic large cell lymphoma (ALCL) (n = 14) specimens., Results: Complete loss of 5-hmC nuclear staining by CD30+ cells was observed in 63% of LyP cases, 57% of ALCL cases and 0% of control cases., Conclusions: The presence of 5-hmC+ and CD30+ lymphocytes was highly suggestive of a benign process. In contrast, loss of 5-hmC nuclear staining was highly suggestive of a lymphoproliferative disorder (ALCL or LyP). Under these circumstances, the use of 5-hmC staining can be a useful adjunctive tool for discriminating between neoplastic CD30+ lymphoproliferations and inflammatory/infectious simulators harboring reactive CD30+ cells., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: To report an unusual presentation of a case of Lymphomatoid papulosis(LyP) in a young girl., Material and Methods: A 14-year-old female presented with a history of swelling of the left upper eyelid of two weeks duration. There was a history of trivial trauma prior to the swelling. The patient was diagnosed as having pre-septal cellulitis elsewhere and was put on oral antibiotics. The lesion was non-responsive to oral antibiotics. The patient was then referred to our hospital. Ocular examination revealed an elevated lesion measuring 15 mm × 10 mm on the left upper eyelid, associated with pre-septal swelling and induration. Ocular movements were normal. The anterior and posterior segment examination was normal. Incision biopsy was done from the eyelid lesion. Multiple cutaneous lesions were also biopsied., Results: The histopathology examination confirmed the diagnosis of lymphomatoid papulosis type C. Dermatological and systemic evaluation ruled out the other aggressive forms of CD30(+) lymphoid proliferation., Conclusion: We report an unusual presentation of lymphomatoid papulosis(LyP) type C in a young girl. Complete systemic work up and histopathological evaluation is mandatory in cases of suspicious lesions, not responding to conservative treatment.

Background and Objectives: Primary cutaneous CD30-positive T-cell lymphoproliferative disorders (CD30(+) LPD), including primary cutaneous anaplastic large cell lymphoma (CALCL) and lymphomatoid papulosis (LyP), comprise the second most common group of cutaneous T-cell lymphomas (CTCL). The etiology of these disorders is not known. Isolated limb perfusion (ILP) and isolated limb infusion (ILI) are forms of regional chemotherapy used to treat recurrent tumors of the extremity, most commonly, melanoma. Secondary malignancy following regional therapy is rarely reported., Methods/results: We identified two cases of CD30(+) LPD arising in the affected limbs of patients treated with ILP/ILI. We subsequently performed CD30 immunohistochemical stains on 11 pre- and post-treatment skin specimens from melanoma patients treated with ILP/ILI and found that 5 of the 11 cases showed an increase in CD30(+) lymphocytes following ILP/ILI., Conclusions: We hypothesize that ILP/ILI causes upregulation of CD30 expression in the extremities of treated patients, and suggest that this may be a marker of treatment response. However, a rare but long-term effect may be an increased risk of T-cell cutaneous lymphoproliferative disease in the affected limb., (© 2014 Wiley Periodicals, Inc.)

Background: Cutaneous CD8(+) CD30(+) lymphoproliferative lesions are difficult to classify and encompass entities that follow a benign course to overt lymphoma. In order to identify histopathologic criteria for lesions in this spectrum, a series of such cases was reviewed., Methods: Twenty-eight biopsies from 27 patients with CD8(+) CD30(+) cutaneous lymphoid proliferations were evaluated., Results: Seventeen cases were classified as lymphomatoid papulosis (LyP) 'type D', eight as cutaneous anaplastic large cell lymphoma (C-ALCL) and two as CD8(+) mycosis fungoides (MF) with CD30 expression. Features of LyP included spongiosis and/or parakeratosis (90%), epidermotropism by large lymphocytes (90%), with (80%) or without (10%) small lymphocytes; wedge-shaped infiltrate (70%) with perivascular (100%) and interstitial (80%) pattern; and relative uniformity of CD30(+) large atypical cells (90%). C-ALCL was characterized by ulceration (63%), epidermotropism restricted to small lymphocytes (100%), marked density (63%) and pleomorphism (62%) of CD30(+) large atypical cells, and at least focal extension of infiltrate to subcutaneous tissue (88%). CD8(+) CD30(+) MF had vacuolar interface change and a lichenoid pattern (100%)., Conclusions: We concur with previous authors that distinction of CD8(+) LyP from lymphoma in its differential diagnosis is difficult based on histopathology alone. Nonetheless, we propose that certain histopathologic clues may be helpful in this differential diagnosis., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Accurate diagnosis of lymphoma includes the assessment of lineage-specific markers. Hematopoietic and lymphoid tissues express PAX5 exclusively in pro-B-cell to mature B-cell stages. However, some mature PAX5+ T-cell lymphomas have been reported. We report three cases of primary cutaneous CD30+ T-cell lymphoproliferative disorders (LPDs) with PAX5 expression: one cutaneous anaplastic large cell lymphoma (ALCL) and two cases of lymphomatoid papulosis (LyP). The three patients were 26 years old and female, 75 years old and female, and 65 years old and male. In all cases, Hodgkin's and Reed-Sternberg-like large lymphoid cells were present, positive for CD30, fascin, and PAX5, and negative for CD3, CD4, CD8, CD20, CD45RO, CD56, cytotoxic markers, and Epstein-Barr virus. The ALCL was accompanied by lymphadenopathy; the patient died of progressive disease 5 months after diagnosis. The LyP cases were localized in the skin with spontaneous regression. One case was diagnosed during pregnancy, transformed to ALCL, and ended in death 32 months after diagnosis despite multi-agent chemotherapy. This study is the first to address the clinical significance of PAX5+ primary cutaneous CD30+ T-cell LPDs. These cases were distinct regarding PAX5 expression and a relatively aggressive clinical course versus conventional primary cutaneous CD30+ T-cell LPDs., (© 2012 The Authors. Pathology International © 2012 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd.)

CD30+ lymphoproliferative disorders are the most common group of cutaneous T-cell lymphomas after mycosis fungoides and its subtypes. This group includes lymphomatoid papulosis and CD30+ anaplastic large-cell lymphoma; these 2 entities are the extremes of a spectrum with numerous intermediate varieties in which it is not possible to establish a clear diagnosis based on clinical and histopathologic criteria. CD30+ lymphoproliferative disorders must be differentiated from other lymphoproliferative diseases with CD30+ cells in the tumor infiltrates, such as mycosis fungoides or Hodgkin disease, and also from other inflammatory conditions or nonhematological neoplasms that can include this cell type, such as pityriasis lichenoides et varioliformis acuta or certain mesenchymal tumors (CD30+ pseudolymphomas). In contrast to their systemic homologues, which arise in the lymph nodes, CD30+ lymphoproliferative disorders generally have a good prognosis. It is very important to exclude the presence of a lymphoma of systemic origin with extralymphatic spread, as the prognosis and treatment are different.

Purpose: To report the clinicopathologic features of 3 patients with CD30(+) lymphoid proliferations of the eyelid., Design: Retrospective case series., Participants: Patients with cutaneous CD30(+) lymphoproliferative lesions of the eyelid., Methods: Three patients with CD30(+) non-mycosis fungoides T-cell lymphoid infiltrates of the eyelid were identified. The histories, clinical findings, pathologic features including immunohistochemical staining, treatments, and outcomes were reviewed and compared., Main Outcome Measures: Pathologic findings including immunohistochemical analysis., Results: The patients included an 81-year-old man, an 18-year-old man, and a 42-year-old woman with CD30(+) lymphoid proliferations of the eyelid and adjacent soft tissue. The first patient had an isolated crateriform eyelid lesion that was classified as lymphomatoid papulosis (LyP). The second patient had an isolated multinodular lesion of the eyelid that was classified as cutaneous anaplastic large cell lymphoma (cALCL). The third patient presented with eyelid edema with an underlying mass and was found to have widely disseminated anaplastic large cell lymphoma (ALCL). Diagnoses were dependent on clinical findings., Conclusions: The CD30(+) lymphoid proliferations represent a spectrum of conditions ranging from indolent LyP, to moderately aggressive cALCL, to highly aggressive ALCL. Interpretation of the pathologic findings in CD30(+) lymphoid proliferations is based in part on clinical findings., Financial Disclosure(s): The authors have no proprietary or commercial interest in any material discussed in this article., (Copyright (c) 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

A 12-year-old boy had lesions clinically and histopathologically consistent with lymphomatoid papulosis (LP) which were persistent and appeared grouped in a circumscribed area of normal looking background skin on the right abdomen. Staging work-up did not disclose systemic disease. Persistent agmination of lymphomatoid papulosis (PALP) is somewhat different from classical LP because it involves a circumscribed, patch-sized area of the skin and the papules within never resolve completely despite some waxing and waning. PALP might be considered a localized or regional form of LP or a distinct lymphoproliferative disorder; in any case, at least a cautious long-term follow up is recommended, with attention to the possible development of true lymphoma.

Objective: To investigate the clinicopathologic features, immunophenotype and prognosis of lymphomatoid papulosis (LyP)., Methods: Clinicopathologic analysis, immunohistochemical staining (LSAB and EliVision method) and in situ hybridization for EBER were undertaken in this study., Results: Thirteen cases of LyP were studied, derived from six male and seven female patients with a median age of 26.4 years. The most common presentation was multiple symptomless papules or nodules, involving predominately the extremities and trunks. Histologically, the tumor primarily involved the dermis and subcutaneous layer. Six tumors were type A, one was type B and six were type C. The main infiltration patterns were wedge-shaped, band-like, sheet-like or nodular. There was epidermotropism in eight cases. Immunohistochemical staining showed that the large tumor cells in all 12 types A and C cases expressed CD30. All 13 cases expressed two to three T-cell associated antigens (CD3, CD5 or CD45RO) and one to three cytotoxic granule associated antigens (TIA-1, GrB or Perforin). All cases expressed CD4, four expressed CD8, and one expressed CD15. Only one case expressed CD20; and all cases were negative for ALK-1. The tumor cells showing epidermotropism had CD3(+), CD4(+) and CD8(-) phenotype in most cases. Only one case was EBER1/2 positive. Follow up information was available in 12 patients; all were alive at the end of the follow up period., Conclusions: LyP has distinctive clinicopathologic features and immunophenotype with favorable prognosis. In types A and C, the atypical cells showing epidermotropism were similar to those in MF, these cells possess cerebriform and hyperchromatic nuclei. The epidermotropic tumor cells and the CD30(+) large cells may be derived from different clones. EB virus may not be correlated with LyP.

We elaborate on the diagnosis of CD30 positive cutaneous lymphoproliferative conditions including the various clinical and pathological presentations, our understanding of its pathomechanisms and prognostic implications. The most common reactive conditions that can simulate CD30 lymphoproliferative conditions, including arthropod bite reactions, various viral infections, pityriasis lichenoides and lymphocytic papules in myelodysplastic syndrome, are discussed in detail.

Background: CD30 is expressed in various types of cutaneous lymphomas, including lymphomatoid papulosis (LyP), primary cutaneous anaplastic large cell lymphoma (C-ALCL), some cases of mycosis fungoides showing large cell transformation (MF-TR) and skin localizations of systemic anaplastic lymphoma kinase (ALK)-positive or ALK-negative ALCL. Differentiation between these entities is often not possible on the basis of histology alone, but several markers, including TRAF1, MUM1 and BCL2, have been reported to provide additional diagnostic information., Objective: To evaluate the diagnostic and prognostic significance of these markers in a large group of cutaneous CD30-positive lymphoproliferations., Methods: An immunohistochemical study on the expression of TRAF1, MUM1, BCL2 and CD15 was performed on skin biopsies from 28 patients with C-ALCL, 39 patients with LyP, 11 patients with CD30-positive MF-TR, two with ALK-positive ALCL and six with ALK-negative ALCL. In addition, the prognostic significance of these markers was evaluated., Results: TRAF1 was expressed in roughly 70-80% and MUM1 was expressed in 70-100% of all the groups of cutaneous CD30-positive lymphoproliferations. Highest levels of BCL2 were expressed in MF-TR (73%), in contrast to 21% in C-ALCL and 36% in LyP. Highest levels of CD15 were expressed in C-ALCL (43%), compared with 18% in LyP and 9% in MF-TR. A relationship with survival was not clear., Conclusions: The results of the present study suggest that TRAF1, MUM1, BCL2 and CD15 cannot be considered as useful diagnostic or prognostic marker in cutaneous CD30-positive lymphoproliferations. Differentiation between these different conditions should be based on a combination of clinical, histological and immunophenotypical criteria.

Clusterin expression is common in systemic and cutaneous anaplastic large cell lymphoma (ALCL). Mycosis fungoides (MF) in large cell transformation can resemble ALCL. In this study, we immunohistochemically assessed for clusterin in 97 skin biopsy specimens, including 70 MF cases and 27 other cutaneous neoplasms including ALCL, peripheral T-cell lymphoma unspecified (PTCL), and lymphomatoid papulosis (LyP). Clusterin was positive in 36 (51%) of 70 cases of MF and correlated with clinical stage in 68 cases: 3 of 21 stage I, 11 of 20 stage II, and 23 of 27 stage III/IV. Clusterin expression also correlated with type of skin lesion (3/19 patch, 13/28 plaque, and 20/23 tumor/erythroderma) and number of large cells (6/30 small cell, 12/18 with increased large cells, and 18/22 with large cell transformation). Clusterin expression was not specific for MF as it also was positive in 3 of 3 cases of LyP, 2 of 2 systemic ALCL cases involving skin, 7 of 16 cutaneous ALCLs, and 1 of 6 PTCLs.

In the course of daily sign-out, histopathologists are confronted with instances in which the histopathologic findings may simulate another entity. At times, it can be extraordinarily difficult to distinguish the simulacra from the authentic. Sometimes this happens because different conditions rarely may show nearly identical histopathologic findings. Other times the most prominent histopathologic findings are not the diagnostic ones, yet they may closely resemble a specific entity that is wholly unrelated to the diagnosis. An example of each of these types of mimicry is presented in conjunction with a discussion of the associated pitfalls in diagnosis. Last, a brief discussion of different categories of histopathologic mimicry is presented.

Background: Primary cutaneous CD30+ lymphoproliferative disorders include lymphomatoid papulosis (LyP) and primary cutaneous CD30+ anaplastic large T-cell lymphoma (ALCL). Because of overlapping histological features, it is impossible to distinguish ALCL from LyP on histological grounds. MUM1 (Multiple Myeloma oncogene 1) is expressed in systemic ALCL and classical Hodgkin lymphoma. MUM1 expression has not been studied in detail in CD30+ lymphoproliferative disorders., Objectives: To examine the expression of MUM1 in CD30+ lymphoproliferative disorders and to assess its value as a diagnostic marker., Methods: Thirty-one formalin-fixed paraffin-embedded specimens of LyP (n = 15), primary cutaneous ALCL (n = 10), secondary cutaneous infiltrates of systemic ALCL (n = 4) and secondary cutaneous Hodgkin lymphoma (n = 2) were analysed by immunohistochemistry with a monoclonal antibody against MUM1., Results: Positive staining for MUM1 was observed in 13 cases of LyP (87%), two cases of primary cutaneous ALCL (20%), four cases of secondary cutaneous ALCL (100%) and two cases of secondary cutaneous Hodgkin lymphoma (100%). In 11 of 13 LyP cases (85%), MUM1 was displayed by the majority, i.e. 50-90%, of the tumour cells. In contrast to LyP and secondary cutaneous ALCL, only two cases of primary cutaneous ALCL (20%) harboured MUM1-positive tumour cells. There was a statistically significant difference in the expression of MUM1 between LyP and primary cutaneous ALCL (P = 0.002) and between primary cutaneous ALCL and secondary cutaneous ALCL (P = 0.015)., Conclusions: MUM1 expression is a valuable tool for the distinction of LyP and ALCL and thus represents a novel adjunctive diagnostic marker in CD30+ lymphoproliferative disorders.

Background: Abnormal cell proliferation, which results from deregulation of the cell cycle, is fundamental in tumorigenesis., Objectives: To investigate the expression of proliferation markers and cell cycle regulators in a range of T cell lymphoproliferative skin diseases., Methods: We studied skin specimens of 51 patients with parapsoriasis (PP), mycosis fungiodes (MF), or lymphomatoid papulosis (LyP). Immunohistochemistry was performed for Ki-67, proliferating cell nuclear antigen (PCNA), minichromosome maintenance protein 7 (MCM7), and p21., Results: MF with stage IIB-IV and LyP showed a significantly greater number of Ki-67-positive cells than PP (P=0.02 and 0.001) and MF I-IIA (P=0.019 and 0.003), respectively. MCM7 staining revealed significantly higher labeling indices for MF IIB-IV and LyP when compared to PP (P=0.002 and 0.04) and MF I-IIA (P=0.0005 and 0.01), respectively. Compared to PP and MF I-IIA, MF IIB-IV was associated with significantly higher labeling indices for PCNA (P=0.006 and 0.0004). p21 staining was significantly increased in MF IIB-IV and LyP when compared to PP (P=0.006 and 0.003) and MF I-IIA (P=0.003). However, p21 staining was all in all very weak., Conclusions: Ki-67 and PCNA seem to be useful immunohistological parameters for the correlation with the clinical stage of MF. In the differentiation and prognostication of T cell lymphoproliferative skin disorders, MCM7 may serve as a novel biomarker which is, in contrast to Ki-67 and PCNA, stable throughout the cell cycle.

Background: Inhibitor of DNA binding 2 (Id2), a helix-loop-helix protein of the inhibitor of differentiation (ID) family, is involved in hematopoiesis, mainly through interaction with the E-family of transcription factors. Recent studies have shown that Id2 is overexpressed in some types of B-cell lymphoma, including classical Hodgkin lymphoma. The authors of the current study hypothesized that Id2 also is overexpressed in T-cell lymphomas., Methods: By using reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot analyses, high Id2 messenger RNA (mRNA) and protein levels, respectively, were detected in all 4 T-cell anaplastic large cell lymphoma (ALCL) cell lines that were tested., Results: Immunohistochemistry results indicated that Id2 was expressed strongly in 21 of 27 (78%) ALCL tumors (79% anaplastic lymphoma kinase [ALK]-negative and 75% ALK-positive), in 5 of 10 (50%) extranodal natural killer/T (NK/T)-cell lymphomas of the nasal type, in 2 of 8 (25%) cutaneous ALCLs, in 2 of 9 (22%) enteropathy type T-cell lymphomas, in 1 of 5 (20%) peripheral T-cell lymphomas not otherwise specified, and in 1 of 8 (13%) T-cell prolymphocytic leukemias. Other types of T-cell lymphoma were negative for Id2. Because it is known that myc is expressed in ALCL, myc was inhibited selectively in 2 ALCL cell lines, resulting in a concentration-dependent decrease in Id2 mRNA and protein levels. Conversely, forced expression of myc in HEK 293T cells using an myc/green fluorescent protein adenoviral vector resulted in Id2 up-regulation., Conclusions: Taken together, the current data suggest that Id2 commonly is overexpressed in highly proliferative T-cell lymphomas, and its expression may result from transcriptional activation of myc in these tumors.

Background: Lymphomatoid papulosis (LyP) is a self-healing eruption in the spectrum of CD30+ lymphoproliferative disorders. The most common lymphoproliferative disorder associated with LyP is the most common form of cutaneous T-cell lymphoma: mycosis fungoides., Objective: We sought to describe a distinct entity on the spectrum of CD30+ lymphoproliferative disorders., Results: Seven patients presented with similar findings. Within a well-circumscribed area, the size and location of a patch of mycosis fungoides, these patients had continual eruptions of papulonodules that were histologically typical of LyP. The localized areas of involvement were treated as oligolesional mycosis fungoides and long-standing remissions occurred even after years of experiencing continuous localized eruptions. The clinical and histologic findings are reviewed and presented in a way to further the identification of patients with this entity., Limitations: This distinct entity is only defined by 7 patients., Conclusion: The agmination of LyP-like papulonodules confined to a discrete circumscribed area is a distinct clinical subset within the spectrum of CD30+ lymphoproliferative disorders. The behavior of this entity is that of a progressive lymphoma that warrants therapy.

Lymphomatoid papulosis (LyP), primary cutaneous anaplastic large T-cell lymphoma (cALCL), and cutaneous infiltrates of systemic anaplastic large cell lymphoma (sALCL) are CD30-positive lymphoproliferative disorders of the skin that overlap clinically, histopathologically, immunophenotypically, and genetically but differ considerably in their prognosis. In particular, lesions of LyP regress spontaneously, whereas those of cALCL and sALCL persist and may progress and spread to extracutaneous sites. In contrast to patients with cALCL, LyP patients do not benefit from an aggressive radio- and/or chemotherapeutic approach. We generated a novel tumor necrosis factor receptor (TNFR)-associated factor 1 (TRAF1) antibody that recognizes a formalin-resistant epitope (Ber-TRAF1A) and investigated the expression of TRAF1, an intracellular component of TNFR signaling, in LyP and ALCL. We could show a strong TRAF1 expression in the tumor cells of most LyP cases (42/49, 84%). In contrast, tumor cells of primary and secondary cALCL revealed TRAF1 expression in only a few cases (3/41, 7%) as shown for sALCL without skin manifestation. The data indicate that TRAF1 expression reliably distinguishes LyP from primary or secondary cALCL. This might be of crucial diagnostic importance and has a strong impact on the treatment decision for patients with cALCL and LyP.

Although CD1a+ dendritic cells (DC) in cutaneous T-cell lymphomas (CTCL) have been well documented, the presence of large numbers of DC within lymphoid infiltrates can pose a diagnostic difficulty. We present a case of a 70-year-old man with a 3-year history of recurrent red papules and plaques on the extremities and trunk that was referred to our institution, with the diagnosis of Langerhans cell histiocytosis. Skin biopsies showed a wedge-shaped cellular infiltrate in the superficial and deep dermis consisting of two cell populations. Most prominent were clusters of epithelioid cells with grooved nuclei and abundant eosinophilic cytoplasm, which stained with antibodies to CD1a and S-100. A second, less prominent population of atypical lymphocytes, some with enlarged, hyperchromatic and convoluted nuclei, were intermixed. The latter were positive for CD30, CD3 and CD5 and negative for CD20, CD34, CD68, ALK-1 and TdT. T-cell receptor gene rearrangement studies confirmed a clonal T-cell population, which with the clinical history was consistent with the diagnosis of lymphomatoid papulosis. While previous studies have shown an increased density of dermal DC in CTCL, we believe that this represents the first report of an unusually florid DC proliferation mimicking Langerhans cell histiocytosis and masking a lymphoproliferative disorder.

Cellular Jun (c-Jun), a member of the JUN family, is an activator protein-1 transcription factor involved in cell differentiation, proliferation, and apoptosis that can be activated by phosphorylation at serine-73 and -63 residues. Using tissue microarrays and immunohistochemistry, we investigated c-Jun expression and serine-73 phosphorylation in 112 CD30 lymphomas and 232 CD30 lymphomas of B- or T-cell lineage, and 24 cases of lymphomatoid papulosis. c-Jun was expressed exclusively by CD30 lymphoproliferative disorders including 41/41 (100%) classical Hodgkin lymphoma (cHL), 20/23 (87%) anaplastic lymphoma kinase (ALK)+ anaplastic large cell lymphoma (ALCL), 18/26 (69%) ALK- ALCL, 5/9 (56%) primary cutaneous ALCL, 4/11 (36%) CD30 diffuse large B-cell lymphoma (DLBCL), and 11/24 (46%) cases of lymphomatoid papulosis. The percentage of c-Jun-positive tumor cells was highest in cHL and ALCL (P=0.002). In contrast, all CD30 lymphomas, including nodular lymphocyte predominant HL and CD30 non-Hodgkin lymphomas of B- or T-cell lineage were negative for c-Jun. Serine-73 phosphorylated c-Jun (p-c-Jun), the activated form of c-Jun, was expressed more frequently and at a higher level in cHL and ALK+ ALCL than other CD30 tumors. The percentage of p-c-Jun-positive tumor cells correlated significantly with the percentage of total c-Jun-positive cells (P<0.0001), suggesting that activated c-Jun positively regulates total c-Jun levels in CD30 lymphomas through a well-established positive feedback loop. We conclude that CD30 lymphomas are characterized by common patterns of c-Jun expression and activation suggesting a potential role of c-Jun in the pathogenesis of these tumors.

We describe 5 cases (4 males, 14-43 years old; 1 female, 61 years old) of primary cutaneous T-cell lymphoproliferative lesions expressing a CD8/granzyme/CD30-positive phenotype. Four cases were compatible with lymphomatoid papulosis (LyP) based on the clinical course, which was recurrent asymptomatic papular nodular lesions over years responding to methotrexate; granulomatous inflammation and lack of other inflammatory cell elements were characteristic. In 1 case, an initial erroneous diagnosis was made of aggressive epidermotropic CD8+ T-cell lymphoma. The fifth case in this series was first interpreted as representing primary cutaneous anaplastic large cell lymphoma but was later recategorized as primary cutaneous aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma owing to the extent of extracutaneous dissemination, including testicular involvement and disease progression despite chemotherapeutic intervention. Although all cases of LyP showed sharp cytoplasmic membrane staining with perinuclear Golgi accentuation with CD30, the recategorized case of aggressive epidermotropic CD8 cytotoxic T-cell lymphoma manifested only a weak cytoplasmic staining pattern. CD8 LyP defines a distinctive entity with characteristic light microscopic and phenotypic findings and has a predilection for young males. CD30 expression can occur in other forms of CD8 lymphoproliferative disease unrelated to primary cutaneous anaplastic large cell lymphoma or LyP.

JunB is a member of the Jun family of proteins that are components of the AP-1 transcription factor complex. AP-1 is involved in cell proliferation and apoptosis. Recent evidence suggests that Hodgkin and Reed-Sternberg cells overexpress JunB and that JunB facilitates constitutive CD30 expression by binding to an AP-1 site in the CD30 promoter. In this study we surveyed JunB expression in a variety of CD30+ lymphoma types including 42 cases of anaplastic large cell lymphoma, 36 classical Hodgkin lymphoma, 15 cutaneous anaplastic large cell lymphoma, and 11 CD30+ diffuse large B-cell lymphoma. In addition, seven cases of nodular lymphocyte-predominant Hodgkin lymphoma and 42 diffuse large B-cell lymphoma, known to be CD30-, were analyzed. JunB expression was assessed using tissue microarrays, immunohistochemistry and a monoclonal antibody specific for JunB. Expression of JunB was observed in 41 of 42 cases of anaplastic large cell lymphoma, including all 21 cases positive for anaplastic lymphoma kinase and 20 of 21 (95%) negative for anaplastic lymphoma kinase. JunB was also expressed in all cases of classical Hodgkin lymphoma, cutaneous anaplastic large cell lymphoma and CD30+ diffuse large B-cell lymphoma, and in lymphomatoid papulosis. By contrast, all nodular lymphocyte-predominant Hodgkin lymphomas and diffuse large B-cell lymphomas that were CD30- were also JunB-. We conclude that JunB is expressed in virtually all CD30+ lymphomas and is a potential target for experimental therapy in patients with these tumors.

Background: The CD30-positive lymphoproliferative disorders lymphomatoid papulosis (LyP), primary cutaneous anaplastic large cell lymphoma (C-ALCL), and systemic anaplastic large cell lymphoma (S-ALCL) are lesions that overlap clinically, histopathologically, and immunophenotypically. Their biologic behaviors, however, vary considerably. In particular, lesions of LyP regress spontaneously while those of S-ALCL persist and often progress. Apoptosis has been suggested as the mechanism by which the lesions of LyP regress, but the underlying signaling pathways remain unclear. In this study, we used newly developed activation state-specific antibodies to demonstrate apoptosis signaling through the death receptor-mediated pathway regulated by FADD and caspase 3., Methods: Dual immunohistochemistry for CD30 and activated forms of FADD and caspase 3 was performed on cutaneous biopsy specimens from 27 patients with CD30-positive lymphoproliferative disorders involving the skin. The patients included 18 with primary cutaneous CD30-positive LPDs (15 with LyP and 3 with C-ALCL) and 9 with S-ALCL., Results: The proportion of CD30-positive cells expressing activated FADD was significantly different between primary cutaneous CD30-positive lymphoproliferative disorders and S-ALCL (36.4% vs. 14.5%, P = 0.0083). Expression of cleaved caspase 3 was also significantly different between primary cutaneous lesions and S-ALCL (9.2% vs. 1.9%, P = 0.048)., Conclusions: Although a larger number of cases should be studied to validate these results, these data provide evidence that differences in signaling through the death-receptor apoptosis pathway mediated by FADD may be responsible for the varying biologic behaviors of CD30-positive lymphoproliferative disorders involving the skin.

c-Kit receptor (CD117) is expressed by erythroid, megakaryocytic, and myeloid precursors and mature mast cells and has been reported to be expressed in CD30+ lymphomas such as Hodgkin's disease and anaplastic large-cell lymphoma. Imatinib mesylate, a well-established inhibitor of bcr-abl tyrosine kinase, and currently used for the treatment of patients with chronic myeloid leukemia, also inhibits c-kit receptor kinase activity. In view of the possible use of imatinib as experimental therapy for patients with c-kit-positive tumors, we assessed c-kit expression in CD30+ cell lines and lymphomas. The cell lines were assessed using multiple methods (RT-PCR, flow cytometry, and Western blot). c-Kit expression was also immunohistochemically assessed in 168 CD30+ lymphomas including 87 classical Hodgkin's disease, 63 anaplastic large-cell lymphoma, and 15 cutaneous anaplastic large-cell lymphoma. We also studied 18 cases of lymphomatoid papulosis, a CD30+ lesion closely related to cutaneous anaplastic large-cell lymphoma. Neither c-kit mRNA nor protein was detected in any of the cell lines assessed. Furthermore, treatment with imatinib did not inhibit proliferation of cell lines in vitro. Using immunohistochemistry, only one of 183 (0.5%) lesions was positive for c-kit, the positive case being an ALK-negative anaplastic large-cell lymphoma. Our data demonstrate that expression of c-kit receptor is exceedingly rare among CD30+ lymphomas and lymphomatoid papulosis, suggesting that c-kit receptor is unlikely to be an appropriate target for therapeutic options such as imatinib in patients with these tumors.

We report a patient presenting with a 20-year history of recurrent papulonecrotic lesions in which skin biopsy shows extensive vascular destruction. Atypical lymphoid cells surrounding the dermal vessels had a CD3+, CD4-, CD5-, CD8+, CD20-, CD30+, CD56+, TIA-1+, and granzyme B immunophenotype implicating a natural killer/T origin. In situ hybridization was negative for Epstein-Barr virus transcripts. Analysis of T-cell receptor-gamma gene of 2 separate biopsy specimens detected an identical clone. The patient was treated with low-dose methotrexate and achieved complete resolution in a month. According to the clinical course, immunophenotype, clonality analysis and the excellent response to methotrexate, we conclude that this is an unusual case of lymphomatoid papulosis. We believe that this unusual presentation needs to be distinguished from other aggressive lymphomas, including the natural killer/T-cell and cytotoxic T-cell subsets.

CD30-positive cells characterize lymphomatoid papulosis and anaplastic large cell lymphoma but can also be found in nonneoplastic skin disorders. Purportedly, CD30 is useful in the differential diagnosis between insect bites and lymphomatoid papulosis. Recently, a subtype of neutrophil-rich CD30-positive anaplastic large cell lymphoma has been described, which may enter the differential diagnosis of cutaneous neutrophil-rich inflammatory infiltrates. We studied atypical CD30-positive lymphoid cells in five eosinophil-rich and 23 neutrophil-rich common nonneoplastic skin infiltrates. The eosinophil-rich cases included five insect bites. The neutrophil-rich cases included 9 inflammatory (hidradenitis suppurativa [n = 4], stasis ulcer [n = 2], ruptured cyst, rhynophyma, and Sweet syndrome); 12 infectious (bacterial [n = 8], viral [n = 2] and fungal [n = 2] etiologies); and 2 environmental (spider bites) cases. Atypical CD30-positive cells were found in 4 of 5 eosinophil-rich, 8 of 9 neutrophil-rich inflammatory, 6 of 12 neutrophil-rich infectious, and 2 of 2 neutrophil-rich environmental cases. Polymerase chain reaction analysis for B- and T-cell clonality and cell counts of neutrophils, eosinophils, plasma cells, B cells (using CD20), and T cells (using CD3) were performed in the cases that contained atypical CD30-positive lymphoid cells. CD30-positive cells averaged 4.8% of the cells counted in the areas where they were most concentrated. Of the 18 cases that amplified with polymerase chain reaction, all were polyclonal for T-cell receptor rearrangements; 10 were polyclonal and 8 oligoclonal for B-cell immunoglobulin rearrangements. There was no correlation between B-cell oligoclonality with CD30-positive cell counts, a particular disease, or a disease category. In conclusion, the presence of CD30-positive atypical lymphoid cells in 71.4% of the common nonneoplastic cases studied, even in the presence of clonal B-cell populations, warrants caution in the interpretation of these cells as malignant, particularly when dealing with the differential diagnosis of lymphomatoid papulosis or neutrophil-rich anaplastic large cell lymphoma.

We describe 9 patients with a novel variant of lymphomatoid papulosis characterized by prominent localization of the infiltrate around the eccrine coil, resulting in nodular expansion of the coil accompanied by variable granulomatous inflammation. Light microscopy, immunohistochemical analysis using antibodies to CD2, CD3, CD4, CD5, CD7, CD8, and CD30 in 6 cases, and polymerase chain reaction--single-stranded conformational polymorphism analysis for T-cell receptor gamma chain gene rearrangement in 5 cases revealed 2 cytomorphologic patterns (large cell dominant with polymorphous inflammation, small cell lymphocyte--rich with an inconspicuous large cell component [phenotypes, CD30+/CD3+/CD4+/CD7-for large atypical cells; reactive for small lymphocytes]) and clonal restriction in 4 and polyclonality in 1 of the lymphocyte-dominant cases. During an average 6-year follow-up, no lymphomas developed. Recognition of this variant is important--accentuation of the infiltrate around the eccrine coil and cutaneous nerves, presence of granulomatous inflammation, dominance of small lymphocytes in the dermis, and variable extension into the panniculus may lead to diagnostic confusion with entities such as discoid lupus erythematosus, Jessner lymphocytic infiltrate of skin, subcutaneous T-cell lymphoma, and persistent arthropod bite reaction. Our findings suggest that pruritus, a younger age at diagnosis, and a more indolent course are defining clinical features.

Lymphomatoid papulosis is a chronic recurrent eruption of self-regressing papules and nodules. Histologically this disorder is characterized by large atypical lymphoid cells resembling Reed-Sternberg (RS) cells that are set in a background of a mixed inflammatory infiltrate. Depending on the architecture of the infiltrate and the percentage of atypical cells, the histologic appearance is subclassified as type A, B, or C. The different histologic patterns do not seem to correlate with distinct clinical appearances. We report a case of lymphomatoid papulosis with unusual histologic features affecting a 14-year-old girl. The presence of anaplastic cells in a background of myxoid stroma closely resembled a sarcoma on histologic examination.