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Cutaneous pseudolymphomas are a wide group of diseases mimicking cutaneous lymphoma. They comprise several skin conditions with different etiopathogenesis, clinical-pathological features, and prognosis, which may occur in the absence of an identifiable trigger factor or after administration of medications or vaccinations, tattoos, infections, or arthropod bites. They present with different manifestations: from solitary to regionally clustered lesions, up to generalized distribution and, in rare cases, erythroderma. They persist variably, from weeks to years, and resolve spontaneously or after antibiotics, but may recur in some cases. CD30+ T-cell pseudolymphomas are characterized by the presence of large, activated lymphoid cells, generally in response to viral infections, arthropod assault reactions, and drug eruptions. Stenotrophomonas maltophilia is a ubiquitous Gram-negative bacillus responsible for opportunistic infections in immunocompromised patients. Infection of intact skin in immunocompetent patients is particularly rare. Here, we report a case of a man presenting an isolated nodule histopathologically mimicking a primary cutaneous CD30+ T-cell lymphoproliferative disorder., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Cutaneous lymphoid hyperplasia (CLH), also known as cutaneous pseudolymphoma, is a spectrum of benign conditions characterized by reactive B- and T-cell cutaneous lymphocytic infiltrates. B-cell lymphoid proliferations are a heterogenous group of non-neoplastic cutaneous diseases that must be histopathologically distinguished from cutaneous B-cell lymphomas. These proliferations can be observed as reactive phenomena to infections, medications, allergens, neoplasms, and more. Furthermore, there are many inflammatory conditions that present with reactive B-cell infiltrates, including actinic prurigo, Zoon balanitis, Rosai-Dorfman disease, and cutaneous plasmacytosis. This review summarizes multiple cutaneous B-cell lymphoid proliferations within the major categories of reactive and disease-associated CLH. Further we discuss major discriminating features of atypical CLH and malignancy. Understanding the specific patterns of B-cell CLH is essential for the proper diagnosis and treatment of patients presenting with such lesions., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Subcutaneous vaccination or desensitization may induce persistent nodules at the injection sites. Without the knowledge of prior injection, histopathological work-up may be challenging., Objective: Aim of this study was to contribute to the histopathological work-up of unclear subcutaneous nodules, especially their differentiation from cutaneous lymphoma., Methods: We retrospectively reviewed clinical data and histopathological slides of four patients with subcutaneous nodules, which were suspected to suffer from cutaneous T- or B-cell lymphoma. Sections of these cases and 12 negative controls were stained with hematoxylin and eosin and a standardized immunohistochemical panel of B- and T-cell markers including EBER in situ hybridization as well as electron microscopy., Results: In all cases, large histiocytes with granular cytoplasm compatible with intracellular aluminum hydroxide were present. EBER in situ hybridization revealed positive staining of these granular histiocytes while staining was absent in negative controls., Limitations: Post hoc completion of medical history revealed that vaccination or specific immunotherapy had been applied before at the biopsy site in only three out of four patients; one patient was lost to follow-up., Conclusion: EBER in situ hybridization is an adjunctive tool to differentiate aluminum-induced granuloma/lymphoid hyperplasia from other forms of pseudolymphoma and cutaneous B- or T-cell lymphomas., (© 2021 The Authors. Journal of Cutaneous Pathology published by John Wiley & Sons Ltd.)

Cutaneous pseudolymphomas (PSLs) belong to a group of lymphocytic infiltrates that histopathologically and/or clinically simulate lymphomas. Different causative agents (e.g., Borrelia sp., injected substances, tattoo, arthropod bite) have been described, but in many cases no cause can be identified, hence the term idiopathic PSL. Clinicopathological correlation is important to make the diagnosis. Four main groups of cutaneous PSL can be distinguished based on histopathologic and/or clinical presentation: (a) nodular PSL; (b) pseudo-mycosis fungoides (pseudo-MF) and simulators of other CTCLs; (c) other PSL (representing distinct clinical entities); and (d) intravascular PSL. This article gives an overview of the histopathologic and clinical characteristics of cutaneous PSLs and proposes a new classification., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: In cases of herpes virus infection without typical histologic (and clinical) signs it is difficult to achieve the correct diagnosis by histology alone. Some of those cases are prone to be misdiagnosed as cutaneous lymphoma., Methods: This retrospective study included five patients with herpes simplex virus (HSV)-associated pseudolymphoma. We investigated clinical, histomorphologic and immunophenotypic features of all patients., Results: All biopsy specimens presented a superficial and deep perivascular lymphohistiocytic infiltrate with epidermotropism, atypia and admixed plasma cells to varying degrees. Four of five samples showed lining-up of lymphocytes in the junctional zone with predominance of CD8+ lymphocytes, in contrast to the dermal part (inverse CD8:CD4 ratio). Papillary edema was found in four of five cases. Clinically, patchy erythema located on the buttocks and adjacent areas was typical, sometimes with erosions and crusts. Medical history of recurrent blisters, pain or itching was additionally helpful., Conclusion: We point out subtle but consistent histomorphologic criteria, which were helpful to diagnose HSV-associated pseudolymphoma in context with the clinical presentation., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Acral pseudolymphomatous angiokeratoma of children (APACHE) is a disease comprised by a dense dermal infiltrate of B-lymphocytes and T-lymphocytes in which prominent blood vessels with plump endothelium are found. In the past, the lesion was interpreted as a variant of angiokeratoma, a vascular malformation, or a nevus. Currently, most authors consider it to be a type of pseudolymphoma with prominent blood vessels. The latter express CD34 and D2-40, while they lack the expression of Glut-1. The expression of Wilms tumor-1 (WT-1) by APACHE has not yet been studied. In this report, we present a case of APACHE on the right foot of a 4-year-old boy and demonstrate immunoexpression of WT-1 by the blood vessels of the lesion. We also performed serial sections and demonstrated that the WT-1+ vessels with prominent endothelium were D2-40-., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

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., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Lymphoplasmacytic plaque in children has been proposed as a rare, emerging clinicopathologic entity characterized by solitary, extratruncal, asymptomatic papules and plaques that are typically found in healthy young Caucasian females. Biopsy of these lesions reveals a dermal lymphoplasmacytic infiltrate with or without epithelioid granulomas. Two unique patients with lymphoplasmacytic plaque in children are presented in this report, including a 26-month-old female with a lesion on her finger, who represents both the youngest described patient and the first documented with a finger lesion, as well as a 17-year-old young woman with a left thigh lesion, who represents the patient with the longest clinically and histopathologically observed lesion to date. These two additional patients corroborate the experience of lymphoplasmacytic plaque in children in the six previously reported cases and further expand the clinicopathologic spectrum of the disease. Recognition of lymphoplasmacytic plaque in children is important to facilitate distinction from potential differential considerations, including lymphoproliferative disorders and infectious conditions, particularly as the experience to date appears to suggest that lymphoplasmacytic plaque in children represent a reactive (pseudolymphomatous) condition., (Copyright © 2012 John Wiley & Sons A/S.)

Disseminated miliarial-type lymphocytoma cutis is a rare clinicopathologic subtype of lymphocytoma, characterized by numerous translucent micropapules and located on the head and neck. We describe here the clinical, histological and immunological features of miliarial-type perifollicular B-cell pseudolymphoma in two women aged 32 and 49 years presenting with numerous 1-2 mm translucent papules on the head and neck. Microscopic examination revealed features typical of a miniature lymphocytoma cutis with a superficial nodular infiltrate housing small well-circumscribed germinal centers containing tingible body macrophages and surrounded by a distinct mantle zone. The immunohistological profile was also typical of lymphocytoma cutis, and polymerase chain reaction analysis of the IgH gene rearrangement did not show any clonal B-cell population. The lesions resolved spontaneously in one case and improved after treatment with hydroxychloroquine in the second patient. The presentation of this subtype of lymphocytoma is a formidable clinical diagnostic challenge. Rosacea, sarcoidosis, democidiosis, lupus miliaris disseminatus faciei and steroid acne are easy to exclude on the basis of histological profile. However, the miliarial form of primary cutaneous center lymphoma is difficult to rule out. Dermatologists and dermatopathologists should be aware of this unusual form of lymphocytoma cutis, which can be misleading during clinical diagnosis., (Copyright © 2012 John Wiley & Sons A/S.)

Background: We describe a series of previously unreported, distinctive, polypoid solitary T-cell-rich cutaneous pseudolymphomas., Methods: The clinicopathologic features were examined in 17 cases., Results: Patient ages ranged from 16 to 71 years (mean = 38.5) with a female predominance (female : male = 14 : 3). All lesions, clinically diagnosed most often as pyogenic granuloma, presented as a solitary, polypoid, erythematous, papule ranging in size from 2.5 to 7.5 mm (mean = 5.8). Most occurred on the head and neck (7) and trunk (6) with other sites including the thigh (1), shoulder (1) and knee (1). A dense dermal infiltrate composed of mildly atypical lymphocytes with variable numbers of admixed plasma cells and histiocytes was prototypical. Commonly, there was an associated epidermal collarette (16/17), Grenz zone (11/17) or admixed eosinophils (8/17). Prominent vessels lined by plump endothelial cells, reminiscent of high endothelial venules of lymph nodes, were universal and some degree of telangiectasia was also common (12/17). CD3-positive T-cells consisted of an admixture of CD4-positive and CD8-positive forms (15/16). Multiple studies suggested polyclonality (seven cases). No recurrences after lesional excision were noted in the 17 patients with a follow-up range from 24 to 120 months (mean = 46.6)., Conclusion: Although these lesions share histopathologic features of the so-called acral pseudolymphomatous angiokeratoma of children (APACHE), they occur in a completely different clinical setting, present in solitary and polypoid fashion and are T-cell rich. We propose the diagnostic label T-cell-rich angiomatoid polypoid pseudolymphoma for this distinctive but presumably reactive lesion., (Copyright © 2011 John Wiley & Sons A/S.)

Herpes zoster (shingles) is the result of a reactivation of the varicella zoster virus (VZV). Many adults obtain a VZV vaccine in order to prevent zoster. Non-specific injection site reactions and generalized herpes eruptions have been reported to occur, especially in immunocompromised patients. However, these are most often anatomically generalized reactions and histopathologically resemble typical herpes infections. We report a 61-year-old female on immunosuppressant medications for rheumatoid arthritis who presented with a subcutaneous nodule at the site of a recent herpes zoster vaccination. Histopathological examination revealed a dense nodular and interstitial mononuclear infiltrate throughout the mid and deep dermis with extension into the superficial subcutaneous fat. Immunohistochemical staining revealed an admixture of T-cells and B-cells, with a predominance of T-cells. These findings are consistent with a pseudolymphoma (PL), a reactive inflammatory disorder that can resemble cutaneous lymphoma and has rarely been described in herpes infections and post-herpetic scars. In situ hybridization studies for VZV were performed and highlighted occasional deep fibroblasts with nuclear positivity for VZV DNA. A review of post-vaccination reactions and herpes-related PL is discussed with emphasis on using in situ hybridization in establishing the diagnosis.

Primary cutaneous marginal zone B-cell lymphoma (PCMZL) is an indolent low grade B cell lymphoma of the skin, with lack of extracutaneous involvement at the time of diagnosis. Herein we report the case of a patient with rheumatoid arthritis (RA) who developed symmetrical PCMZL lesions on both ear lobes. Lesions occurring symmetrically on ear lobes are more specific for cutaneous lymphoid hyperplasia (CLH) and this kind of symmetrical localization hasn't been reported for PCMZL before. PCMZL is considered to arise from a background of reactive lymphoid hyperplasia and this case point out the concept of CLH and PCMZL spectrum. Association of marginal zone lymphoma with rheumatoid arthritis and resolution of lesions together with the resolution of symptoms due to rheumatoid arthritis after rituximab therapy is another interesting point for this case. To the best of our knowledge PCMZL associated with RA has not been reported previously.

We report two cases of lymphocytoma cutis caused by pierced earrings, with the results of patch tests and X-ray microanalyses on electron microscopy. We detected zinc through scanning electron microscopy from the specimen of Case 1 and gold and titanium through transmission electron microscopy from Case 2. This is the first report to demonstrate the presence of metal fragments in the lesion, which may suggest the remanence of metal for 20 years, bringing about persistent allergic reaction.

Introduction: Drugs may be an important cause of atypical lymphocytic infiltration. Oftentimes, these infiltrates are in the context of pseudolymphomata. We report a patient who developed lymphocytoma cutis temporally associated with initiation of fluoxetine therapy that later went on to develop cutaneous marginal zone B-cell lymphoma. The response of peripheral blood lymphocytes to fluoxetine and other drugs was examined in an attempt to ascertain the potential role for drugs in the propagation of these infiltrates., Materials and Methods: Routine light microscopic analysis and phenotypic studies were performed on tissue obtained from a skin biopsy. Lymphocyte mitogenic studies were carried out using increasing concentrations of fluoxetine, bupropion, and two anticonvulsants., Results: An initial biopsy was consistent with lymphocytoma cutis. The patient stopped fluoxetine associated with lesional regression. The lesions recurred despite being off fluoxetine; a repeat biopsy was compatible with marginal zone lymphoma. Lymphocyte proliferation assays revealed a suppressive effect on T-lymphocyte proliferation at physiologic concentrations. Other tested drugs did not have a similar suppressive effect., Conclusions: Fluoxetine may be associated with pseudolymphomata and marginal zone lymphoma. The inhibitory effects on T-lymphocyte function and more specifically T-suppressor function may lead to excessive antigen-driven B-cell proliferation.

Background: Palpable arciform migratory erythema (PAME) is characterized by large, elevated, reddish annular lesions localized on the upper trunk. As its infiltrate consists predominantly of dense infiltrates of CD4+ lymphocytes with polyclonal T-cell receptor (TCR) gene rearrangement, it has been grouped as a rare member of the T-cell pseudolymphomas., Methods: We performed histology, immunophenotyping, and TCR-gamma gene rearrangement studies in an human immunodeficiency virus (HIV)-positive patient, CDC stage IIIB, who showed a clinically typical PAME., Results: While TCR-gamma gene rearrangement studies showed a polyclonal infiltrate confirming a pseudolymphoma, 85% of skin-infiltrating lymphocytes were CD8+ T cells., Conclusion: PAME may also occur in HIV-positive patients with CD4+ deficiency. Our case demonstrates that regular CD4 counts and immunocompetence are not necessary for its pathogenesis.

Lymphocytoma cutis (LC) is considered as the stereotypical example of the cutaneous B-cell pseudolymphomas. It can be induced by various antigenic stimuli including arthropod bites, vaccination, and drugs among others. In endemic regions, Borrelia burgdorferi is the principal causative agent for LC. We studied retrospectively 108 biopsies from 106 patients (male : female, 48 : 58; mean age, 44.6; median, 51.5; range, 3-81) with B. burgdorferi-associated LC retrieved from the files of the Department of Dermatology of the University of Graz (Austria). Only cases with a B. burgdorferi etiology (typical locations, positivity of serologic and/or polymerase chain reaction (PCR) tests, clinical history) were included in the study. Lesions were located on the nipple (63 cases), earlobe (18 cases), genital region (9 cases), and trunk or extremities (16 cases). PCR analysis of B. burgdorferi DNA was positive in 54 of 80 cases tested (67.5%). In 47 cases, we could retrieve data on serologic examination for B. burgdorferi antibodies performed at the time of diagnosis of LC. Positivity was found in 45 patients (IgG+/IgM+, 5 cases; IgG+/IgM-, 37 cases; IgG-/IgM+, 3 cases; IgG-/IgM-, 2 cases). Histology revealed dense lymphoid infiltrates with prominent germinal centers (GCs) in all cases. Atypical morphologic and/or immunophenotypic features of the GCs were commonly observed. In 5 cases, due to confluence of large follicles, the histopathologic pattern simulated that of a large B-cell lymphoma. PCR analysis of the IgH gene rearrangement performed in 33 cases showed a polyclonal pattern in 31 cases and a monoclonal band in 2. In summary, B. burgdorferi-associated LC can present with misleading histopathologic, immunophenotypic, and molecular features, and integration of all data is necessary for a correct diagnosis.

Background: Molluscum contagiosum (MC) is a common cutaneous infection, which has been reported in association with cutaneous pseudolymphoma in few cases., Methods: A 72-year-old woman with a nodule arising on the external canthus was reviewed. The lesion was surgically removed, and the histopathological study demonstrated an epidermal invagination filled by molluscum bodies and a diffuse infiltrate comprising atypical lymphocytes., Results: Immunohistochemical stains disclosed predominance of T cells with positive CD30 labeling. Polymerase chain reaction failed to demonstrate clonal rearrangement of the T-cell receptor., Conclusion: After ruling out systemic involvement, the patient was followed up for 2 years with no evidence of recurrence. We report this case to the best of our knowledge and discuss the literature about atypical clinical and histological presentations of MC.

Background: Acral pseudolymphomatous angiokeratoma of children (APACHE) is a disorder characterized clinically by red nodules and histopathologically by a massive subepidermal lymphohistiocytic infiltrate. Although it was initially thought to be a vascular nevus, it has never been regarded as a pseudolymphoma., Case Report: We report a 7-year-old-girl with small red nodules on the dorsum of the right foot and a 73-year-old man with asymptomatic brown-red nodules on the lower extremities., Results: Histopathologic examination revealed a massive lymphohistiocytic infiltrate with plasma cells, some eosinophils, or a multinucleated giant cell immediately beneath the epidermis. Thick-walled vessels were observed in the infiltrate. These characteristics are identical to those of acral pseudolymphomatous angiokeratoma of children. The infiltrate was composed mainly of equal numbers of CD4+ or CD8+ T cells and equal numbers of B cells stained for kappa or lambda light chains. PCR amplification of rearranged immunoglobulin heavy chain genes or T-cell receptor gamma genes showed no evidence of clonality, suggesting that these infiltrates were polyclonal both for B and T cells., Conclusions: Our data support the idea that this disorder represents a reactive process. The modified term 'papular angiolymphoid hyperplasia' would define this disorder more appropriately.

Background: Criteria for distinguishing between cutaneous lymphoid hyperplasia (CLH) and low-grade B-cell lymphoma are not well defined. We examined the hypothesis that the presence of a clonal B-cell population in heavy multinodular lymphoid infiltrates correlates with clinical presentation and outcome., Methods: We identified 29 patients with skin lesions characterized histologically by a heavy dermal lymphocytic infiltrate with a multinodular architecture and extension into deep dermis and subcutaneous fat. Clonality was assessed immunophenotypically by light-chain restriction and also by analysis for IgH-gene rearrangement using PCR on DNA extracted from paraffin blocks., Results: Follow-up (mean 80 months; median 45 months) was obtained in all patients. Twenty-four patients (83%) presented with a solitary lesion: only four had solitary recurrences, and none developed multiple synchronous lesions or systemic B-cell lymphoma. However, 9/24 of these solitary lesions (38%) were clonal by light-chain restriction or IgH PCR; 5/29 patients (17%) presented with multiple recurrent lesions and continued to develop lesions during the period of follow-up; 3/5 patients (60%) with multiple lesions demonstrated a B-cell clone. No patient developed systemic B-cell lymphoma., Conclusions: Heavy, multinodular cutaneous lymphoid infiltrates have an excellent prognosis. Multiple lesions at presentation are the best predictor of recurrent multiple lesions confined to the skin. The presence of a clonal B-cell population does not correlate with clinical presentation or histology, nor does it predict development of further lesions or systemic lymphoma.

Background: Cutaneous manifestations of B-cell chronic lymphocytic leukemia (B-CLL) comprise a wide spectrum of clinicopathologic presentations. In some cases, onset of skin lesions is triggered by antigenic stimulation, and specific skin infiltrates at sites of previous herpes simplex or herpes zoster infection have been well documented. Specific skin manifestations of B-CLL can also be observed at sites typical for lymphadenosis benigna cutis (nipple, scrotum, earlobe), a Borrelia burgdorferi-associated cutaneous B-cell pseudolymphoma., Methods: We studied specific skin manifestations of B-CLL arising at sites typical for B. burgdorferi-induced lymphadenosis benigna cutis, analyzing tissues for presence of B. burgdorferi DNA using the polymerase chain reaction (PCR) technique. Six patients with B-CLL (M : F = 4 : 2; mean age: 67.8) presented with specific skin lesions located on the nipple (four cases) and scrotum (two cases)., Results: Clinically there were solitary erythematous plaques or nodules. Histology revealed in all cases a dense, monomorphous infiltrate of small lymphocytes showing an aberrant CD20+/CD43+ phenotype. In all cases monoclonality was demonstrated by PCR analysis of the JH gene rearrangement. PCR analysis showed in four of the six cases the presence of DNA sequences specific for B.burgdorferi., Conclusions: Our study demonstrates that infection with B. burgdorferi can trigger the development of specific cutaneous infiltrates in patients with B-CLL.

Background: Tumor-infiltrating lymphocytes (TILs) are considered to play an important role in the antitumoral immune response. The presence and percentage of CD8-positive tumor-infiltrating T cells have been shown to correlate with differentiation and prognosis in various neoplasms. The aim of this study was to determine the number of CD8-positive T cells in various primary cutaneous B-cell lymphoproliferative disorders and to evaluate its correlation with the histological type of tumor., Methods: Fifty-three lesions were examined by immunohistochemistry with antibodies targeting CD3, CD4, CD8 and TIA-1. Thirty-two lesions had been diagnosed as primary cutaneous B-cell lymphomas (CBCL) and 21 as B-cell pseudolymphomas (B-PSL). CBCLs included 15 follicular lymphomas (FL), 6 marginal zone lymphomas (MZL), and 11 diffuse large B-cell lymphomas (LCL). The number of CD8-positive cytotoxic T cells was determined by computer-assisted morphometrical microscopy., Results: No significant difference could be detected in the density of CD8-positive T cells in B-PSL (101/105 microm(2)), FL (110/105 microm(2)), and MZL (122/105 microm(2)). In contrast, the number of CD8-positive cells (55/105 microm(2)) in LCL was significantly lower (p<0.01) compared to B-PSL, FL and MZL., Conclusions: In summary the number of CD8-positive T cells in B-cell lymphoproliferative disorders differs in regard to tumor type and differentiation with lowest numbers in diffuse large B-cell lymphomas. However, due to an overlap of the number of TILs, this parameter cannot be employed as a diagnostic parameter for individual cases.

Although 2% to 10% of lymphomas present first in the oral cavity and lymphomas are the third most common oral malignancy, pseudolymphoma is a very infrequent problem within oral pathology. Two cases of oral pseudolymphoma are presented. Both were old persons with an infiltrative lesion on the oral mucosa that histologically showed a dense polymorphous infiltrate with some nuclear atypia that raised the problem of lymphoma versus pseudolymphoma. Both lesions disappeared with no relapse after 2-years' follow-up. Histologically, case 1 was mainly a lymphohistiocytic infiltrate whose histiocytic component showed nuclear features that mimicked Hodgkin's cells. In case 2, the infiltrate was mainly composed of histiocytes and eosinophils. The suspicion of malignancy here was a consequence of a high mitotic rate of histiocytes and of the large hyperchromatic nuclei of the intraepithelial lymphocytes. Similarities and differences with other pseudomalignant (lymphomatoid papulosis and atypical histiocytic granuloma) and inflammatory (traumatic ulcerative granuloma with stromal eosinophilia) disorders, as well as with some histiocytoses, are discussed. In the absence of a wider experience on this subject, an objective description of new cases seems appropriate.

After intradermal testing with goldsodiumthiomalate (GSTM), 5 out of 8 patients developed skin papules at the test sites, which persisted up to 20 months. The lesions were surgically excised. Histology revealed pseudolymphoma of B and T cell type containing follicular structures and occasional small granulomas. The amount of histiocytic cells among B and T lymphocytes was pronounced, including acid cysteine proteinase inhibitor (ACPI) positive follicular dendritic cells, CD68 positive macrophages, factor XIIIa positive dermal dendrocytes and S-100 positive cells. By electron microscopy, the macrophages contained endosomes loaded with crystalloid material which contained gold in X-ray microanalysis. Atomic absorption spectrophotometry also confirmed the presence of gold in one specimen. Thus GSTM seemed to accumulate in tissue macrophages leading to constant immunologic activation with lymphoid proliferation and histiocytic response.