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

OUP accepted manuscript

Reactive lymphoid hyperplasia (RLH) of the liver is an extremely rare benign lesion, which is often misdiagnosed as a malignant liver tumour. We present the case of a 69-year-old man with an incidental liver tumour revealed on the ultrasonography of the kidney-urinary bladder system for benign prostatic hyperplasia. Hepatocyte-specific contrast (gadoxetate disodium) magnetic resonance imaging revealed a round 6-mm lesion, which was hypointense on T1-weighted images, slightly hyperintense on T2-weighted images and highly intense on diffusion-weighted images. Other findings included arterial hyperintensity, venous and delayed hypointensity and a defect in liver segment 6. The patient was diagnosed with hepatocellular carcinoma; laparoscopic partial hepatectomy was performed. Intraoperatively, a 7-mm greyish white solid nodule was observed. In conclusion, it may be difficult to distinguish RLH from other malignant liver tumours. However, it should be considered as a differential diagnosis for small liver lesions in young, female patients without liver cirrhosis.

Imaging Manifestations of Intrahepatic Reactive Lymphoid Hyperplasia: A Case Report and Literature Review

Reactive lymphoid hyperplasia (RLH) of the liver is a rare benign disease. This article describes a 77-year-old female patient with RLH of the liver. The patient was admitted to the hospital due to atrial fibrillation. A liver tumor was incidentally found during abdominal enhanced CT. Further magnetic resonance imaging (MRI) and PET/CT showed four lesions in the liver. The imaging findings suggested hepatocellular carcinoma (HCC), but it was not consistent that the patient had no history of liver cirrhosis and hepatitis, and a variety of tumor markers were within the normal range. The largest lesion was surgically removed and microscopically diagnosed as RLH of the liver. The pathology included a large number of reactive hyperplastic lymphoid follicles. Immunohistochemical examination showed that the infiltrating lymphocytes were polyclonal. The authors believe that the perinodular enhancement on MRI, the obvious limitation of diffusion on DWI, the insignificant increase of SUVmax on PET-CT delayed phase, and the support of clinical data can help distinguish liver RLH from lymphoma and HCC.

Differential diagnoses of pseudolymphomatous folliculitis: considerations as regards one case

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

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.

Inflammatory lobular hemangioma: A vascular proliferation with a prominent lymphoid component. Review of a series of 19 cases

In the last 30 years, there has been a strong interest in vascular proliferations. Pyogenic granuloma was not only renamed lobular capillary hemangioma, but also the conceptual interpretation was also changed from an overgrowth of granulation tissue to a genuine hemangioma (or benign vascular neoplasm). We describe 19 cases of patients who presented clinically with a vascular lesion, characteristically a pyogenic granuloma or lobular hemangioma, where the histopathological findings led to the pathologic concern for a lymphoma of the skin. These benign lesions with a dense lymphoid infiltrate were further defined on the basis of different vascular and lymphoid immunohistochemical markers as inflammatory lobular hemangiomas. We propose that given the considerable histopathological overlap between acral pseudolymphomatous angiokeratoma, T-cell rich angiomatoid polypoid pseudolymphoma of the skin, and other designations of some of these vascular proliferations with a rich and dense lymphoid infiltrate, they might constitute a spectrum of vascular lesions with varying clinical presentations.

Kappa and lambda immunohistochemistry and in situ hybridization in the evaluation of atypical cutaneous lymphoid infiltrates

BACKGROUND

Atypical cutaneous lymphoid infiltrates are challenging lesions in dermatopathology. We present a summary of the literature regarding kappa and lambda immunohistochemistry (IHC) and in situ hybridization (ISH) in the evaluation of atypical cutaneous or mucosal lymphoid infiltrates.

METHODS

Relevant articles from 1967 to 2018 in the English language were identified and summarized. In the absence of larger studies, case series of n ≥ 3 were included.

RESULTS

Sixty-three articles assessing kappa and lambda IHC and/or ISH were identified. Most focused on marginal zone lymphomas. Other lymphomas included follicle center lymphoma, diffuse large B-cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, lymphoplasmacytic lymphoma, plasmablastic lymphoma, multiple myeloma, monoclonal gammopathy of undetermined significance, and polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes (POEMS). Non-neoplastic lesions included reactive lymphoid hyperplasia, cutaneous plasmacytosis, connective tissue disease, IgG4-related disease, acrodermatitis chronic atrophicans, Zoon balanitis, dermatitides, and infiltrates around epithelial dysplasias/neoplasias.

CONCLUSION

Kappa and lambda IHC and ISH are useful tools in the evaluation of cutaneous B-cell lymphomas and plasma cell neoplasms. The literature supports that the detection of light-chain restriction by IHC and ISH is one of the most useful findings in the differential diagnosis of reactive lymphoid hyperplasia vs B-cell lymphoma with plasmacytic differentiation.

How I Diagnose Primary Cutaneous Marginal Zone Lymphoma

OBJECTIVES

Primary cutaneous marginal zone lymphoma (PCMZL) is 1 of the 3 major subtypes of primary cutaneous B-cell lymphoma. The diagnosis of PCMZL may be challenging, as the differential diagnosis includes benign cutaneous lymphoproliferations as well as other primary or secondary cutaneous B-cell or T-cell lymphomas. This review describes our approach to the diagnosis of PCMZL.

METHODS

Two cases are presented that illustrate how we diagnose each of the 2 subtypes of PCMZL. The clinicopathologic features of PCMZL and the ways in which these cases can be distinguished from both benign and other neoplastic entities are emphasized.

RESULTS

A definitive diagnosis of PCMZL requires the incorporation of histologic and immunophenotypic features, molecular genetic studies in some cases, and just as importantly, clinical findings. Emerging data suggest that the heavy chain class-switched cases may be more like a clonal chronic lymphoproliferative disorder.

CONCLUSIONS

The 2 subtypes of PCMZL create different diagnostic challenges and require the use of a multiparameter approach. Although very indolent, it is important to distinguish PCMZLs from reactive proliferations, because they frequently recur and may require antineoplastic therapies. It is also critical to distinguish PCMZLs from other B- or T-cell lymphomas so that patients are properly evaluated and not overtreated.

A case of hepatic pseudolymphoma in a patient with primary biliary cirrhosis

Hepatic pseudolymphoma is a very rare benign reactive lymphoid hyperplasia associated with autoimmunity and chronic inflammatory liver diseases such as primary biliary cirrhosis and may mimic hepatocellular carcinoma. This diagnosis should be suspected in female with a suspicious single tumor. Close monitoring is needed in view of its premalignant nature.

Cutaneous Lymphoproliferative Disorders: What's New in the Revised 4th Edition of the World Health Organization (WHO) Classification of Lymphoid Neoplasms

Cutaneous lymphoproliferative disorders remain a challenging aspect of dermatopathology, in part due to the rarity of the entities and extreme variability in clinical outcomes. Although many of the entities remain unchanged, the approach to some of them has changed in the new 2016 classification scheme of the World Health Organization. Chief among these are Epstein-Barr virus-associated lymphoproliferative disorders such as Epstein-Barr virus-associated mucocutaneous ulcer and hydroa vacciniforme-like lymphoproliferative disorder, primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma, primary cutaneous acral CD8+ T-cell lymphoma, primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder, and breast implant-associated anaplastic large cell lymphoma. In addition, translocations and gene rearrangements such as those involving the 6p25.3 locus have started to inform diagnosis and classification of anaplastic large cell lymphoma and lymphomatoid papulosis. In this review, we will examine what is new in the diagnostic toolbox of cutaneous lymphoproliferative disorders.

B-cell Lymphofollicular Infiltrates in Mycosis Fungoides

Aims and background

The histopathological picture of mycosis fungoides can be characterized by heavy reactive infiltrates. These are rarely composed of B lymphocytes with formation of reactive follicles.

Methods and study design

We collected three cases of mycosis fungoides with a reactive B-cell lymphofollicular reaction at the bottom of the epidermotropic infiltrate.

Results

Case 1 showed flat lesions (patches) with a CD4+ neoplastic phenotype; case 2 presented infiltrated lesions (plaques) with a CD8+ immonophenotype; case 3 was characterized by nodular lesions (tumors) with a CD4+ neoplastic component. In all three cases, no clonal gene rearrangement was found with the polymerase chain reaction technique.

Conclusions

Among the protean clinicopathological features which mycosis fungoides can show, we underline that a B-cell lymphofollicular component can be encountered at the base of the epidermotropic infiltrate even in clinically flat (“patchy”) lesions.

Lymphocytoma cutis on the inguinal region: report of a rare case of benign lymphoproliferative disorder

Lymphocytoma cutis, or benign reactive lymphoid hyperplasia, is an inflammatory skin lesion that mimics clinically and histologically malignant lymphoma. Most cases are idiopathic, but they may also be triggered by multiple factors, such as insect bites, tattoos, injections and herpes zoster. Clinically, the lesions are erythematous, soft papules, plaques or nodules, usually located on the upper limbs and face. The diagnosis is mainly based on histopathology and immunohistochemistry. Corticosteroid injections, cryosurgery, PUVA therapy, radiotherapy and surgery can be therapeutic options in cases requiring immediate treatment. To demonstrate an atypical presentation of this tumor, a case lymphocytoma skin on the groin will be reported, describing its diagnosis and treatment.

Disorders characterized by predominant or exclusive dermal inflammation

Some cutaneous inflammatory disorders are typified by a predominant or exclusive localization in the dermis. They can be further subdivided by the principal cell types into lymphocytic, neutrophilic, and eosinophilic infiltrates, and mixtures of them are also seen in a proportion of cases. This review considers such conditions. Included among the lymphoid lesions are viral exanthems, pigmented purpuras, gyrate erythemas, polymorphous light eruption, lupus tumidus, and cutaneous lymphoid hyperplasia. Neutrophilic infiltrates are represented by infections, Sweet syndrome, pyoderma gangrenosum, and hidradenitis suppurativa, as well as a group of so-called "autoinflammatory" dermatitides comprising polymorphonuclear leukocytes. Eosinophil-dominated lesions include arthropod bite reactions, cutaneous parasitic infestations, the urticarial phase of bullous pemphigoid, Wells syndrome (eosinophilic cellulitis), hypereosinophilic syndrome, and Churg-Strauss disease. In other conditions, eosinophils are admixed with neutrophils in the corium, with or without small-vessel vasculitis. Exemplary disorders with those patterns include drug eruptions, chronic idiopathic urticaria, urticarial vasculitis, granuloma faciale, and Schnitzler syndrome (chronic urticarial with a monoclonal gammopathy).

Approach to Cutaneous Lymphoid Infiltrates: When to Consider Lymphoma?

Cutaneous lymphoid infiltrates (CLIs) are common in routine dermatopathology. However, differentiating a reactive CLI from a malignant lymphocytic infiltrate is often a significant challenge since many inflammatory dermatoses can clinically and/or histopathologically mimic cutaneous lymphomas, coined pseudolymphomas. We conducted a literature review from 1966 to July 1, 2015, at PubMed.gov using the search terms: Cutaneous lymphoma, cutaneous pseudolymphoma, cutaneous lymphoid hyperplasia, simulants/mimics/imitators of cutaneous lymphomas, and cutaneous lymphoid infiltrates. The diagnostic approach to CLIs and the most common differential imitators of lymphoma is discussed herein based on six predominant morphologic and immunophenotypic, histopathologic patterns: (1) Superficial dermal T-cell infiltrates (2) superficial and deep dermal perivascular and/or nodular natural killer/T-cell infiltrates (3) pan-dermal diffuse T-cell infiltrates (4) panniculitic T-cell infiltrates (5) small cell predominant B-cell infiltrates, and (6) large-cell predominant B-cell infiltrates. Since no single histopathological feature is sufficient to discern between a benign and a malignant CLI, the overall balance of clinical, histopathological, immunophenotypic, and molecular features should be considered carefully to establish a diagnosis. Despite advances in ancillary studies such as immunohistochemistry and molecular clonality, these studies often display specificity and sensitivity limitations. Therefore, proper clinicopathological correlation still remains the gold standard for the precise diagnosis of CLIs.

Pseudolymphoma of the liver: a case report and literature review

Pseudolymphoma is a benign lymphocytic tumor-like lesion, and its occurrence in the liver is rare. Here, we report the case of a 78-year-old woman with pseudolymphoma of the liver. She had a history of tremors for several years. Therefore, she underwent computed tomography (CT) for screening, and liver tumors were incidentally identified. She did not have any history of liver disease. Liver function test results and tumor marker levels were all within normal limits, and viral markers for hepatitis were negative. Contrast-enhanced CT revealed four nodules measuring up to 13 mm in diameter with ring enhancement in both lobes of the liver. On magnetic resonance imaging, the lesions showed slightly high intensity on T2-weighted images and high intensity on diffusion-weighted images. Because of atypical imaging findings, the tumors could not be definitively diagnosed. Therefore, we performed laparoscopic limited resection of segments 2, 3, 4, and 8 of the liver. The final pathological diagnosis was pseudolymphoma of the liver. The patient has had no signs of recurrence for 6 months after the surgery. Although pseudolymphoma of the liver is rare, it is necessary to consider it in the differential diagnosis of a liver tumor.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Lymphocytoma cutis--case report

We describe a clinical case involving a 62-year-old white male, diagnosed with lymphocytoma cutis (Spiegler-Fendt sarcoid) in the cephalic segment. The diagnosis was carried out by pathological study and confirmed by immunohistochemical panel: evidence of polyclonality. Phototherapy sessions were suggested as treatment (13 PUVA sessions, with an accumulated dose of 58.65 J/cm2 ). The improvement was partial. Thus, infiltration of triamcinolone was opted for (one intralesional infiltration every 3 weeks). After 5 sessions, satisfactory improvement was observed: regression of nearly all the lesions.

Analysis of cutaneous lymphomas in a medical center in Bahia, Brazil

OBJECTIVES

To evaluate the frequency of the different types of cutaneous lymphoma (CL) in 1 university hospital in Brazil and compare this frequency with those observed in other countries.

METHODS

After review, 72 (84.7%) cases of primary cutaneous T-cell lymphoma (CTCL) and 13 (15.3%) cases of primary cutaneous B-cell lymphoma (CBCL) were included.

RESULTS

Of the CTCLs, 40.3% were mycosis fungoides (MF); 26.4% were adult T-cell leukemias/lymphomas (ATLs); 23.6% were peripheral T-cell lymphomas, unspecified; and 8.3% were anaplastic large cell lymphomas. Of the MF cases, 17.2% progressed to transformed MF. Five-year survival for primary human T-cell lymphotropic virus type 1-negative CTCL, ATL, and CBCL was 64.0%, 42.1%, and 62.5%, respectively. MF and ATL were the most frequent primary CTCLs.

CONCLUSIONS

The frequencies observed here are close to those observed in Peru but different from those of European countries. Unfortunately, the World Health Organization/European Organization of Research and Treatment of Cancer classification does not include primary cutaneous ATL.

Mimics of cutaneous lymphoma: report of the 2011 Society for Hematopathology/European Association for Haematopathology workshop

The Society for Hematopathology and European Association for Haematopathology workshop, from October 27 to 29, 2011, in Los Angeles, CA, exhibited many exemplary skin biopsy specimens with interesting inflammatory changes mimicking features of cutaneous lymphoma. This article reviews features observed in cutaneous lymphoid hyperplasia, cutaneous drug reactions, lupus-associated panniculitis, pityriasis lichenoides, hypereosinophilic syndrome, histiocytic necrotizing lymphadenitis, traumatic ulcerative granuloma with stromal eosinophils, and pigmented purpuric dermatosis, as well as a brief review of the pertinent literature and discussion of submitted conference cases. For the pathologist, it is important to be aware of diagnostic pitfalls as well as the limitations of ancillary testing (eg, clonality studies). Finally, correlation with total clinical information, good communication with clinical colleagues, close clinical follow-up with rebiopsy, and prudent use of laboratory studies are vital and will likely offer the best path toward a correct diagnosis.

Profiles of cytotoxic T lymphocytes in cutaneous lymphoid hyperplasia of the face

Cutaneous lymphoid hyperplasia (CLH) is difficult to differentiate from primary malignant cutaneous lymphomas that may present as solitary nodules, and sometimes it requires much time to achieve a final diagnosis. A recent report [Park et al.: Acta Haematol 2011;126:79-86] suggested that the expression of granulysin correlates with the prognosis of cancer patients, even in hematological disorders. In this report, we immunohistochemically examine the expression of cytotoxic molecules (e.g. granulysin, TIA-1 and perforin) in tumor-infiltrating lymphocytes of 10 patients with CLH and 3 patients with cutaneous diffuse large B cell lymphoma, not otherwise specified (CDLBCL-NOS) of the face. In the patients with CLH, the number of granulysin-bearing cells was higher than in the patients with CDLBCL-NOS. In contrast, there was no difference in the number of TIA-1(+) or perforin(+) cells. The present study attempts to explain the different biological behaviors of these two hematological disorders and suggests granulysin as a possible diagnostic tool for CLH and CDLBCL-NOS of the face.

Reactive lymphoid hyperplasia of the liver and pancreas. A report of two cases and a comprehensive review of the literature

BACKGROUND

Reactive lymphoid hyperplasia (RLH) is a rare non-neoplastic extranodal pathology with exceedingly rare occurrence in the liver and pancreas. We present two cases of hepatic RLH, one which had coinciding pancreatic involvement. To the best of our knowledge, concomitant hepatic and pancreatic RLH has not been previously reported. We also present a comprehensive review of the literature on hepatic and pancreatic RLH.

METHODS

An extensive literature search for all published reports on hepatic or pancreatic RLH was conducted. Data on clinical, radiographic and histopathological features were extracted in addition to therapeutic options and outcomes.

RESULTS

Forty-two hepatic and three pancreatic cases of RLH were described in the literature. The mean age of hepatic cases was 58 years, with a male-to-female ratio of above 1:7. Almost 25% of cases were associated with internal malignancy. Four hepatic cases were managed through active observation. The remainder (84%) underwent surgical resection. Due to their small number, no meaningful analysis could be made on the pancreatic cases. No recurrences were identified in any of the reported cases.

CONCLUSION

RLH should be considered in the diagnosis of hepatic nodules where biopsies fail to demonstrate malignant cells. Confirmed RLH lesions should be managed by active observation. Investigation and treatment of any potential source of lymphoid reactivity should be undertaken. More reports on pancreatic RLH need to be studied prior to drawing any useful recommendations on its management.

Primary Cutaneous Folliculotropic and Lymphohistiocytic Anaplastic Large Cell Lymphoma

Background:

Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) is a T-cell lymphoma that presents in the skin and consists of CD30+ anaplastic large lymphocytes with abundant cytoplasm and pleomorphic nuclei. In addition to the classic variant, several other histologic patterns of ALCL have been identified, among them the lymphohistiocytic variant.

Objective and Methods:

We describe a case of the lymphohistiocytic variant of PC-ALCL with a marked follicular involvement. The lesion appeared as a single nodule in the face that completely regressed following biopsy. A diffuse infiltration of lymphocytes and macrophages was seen in the dermis associated with hypertrophied hair follicles, follicular mucinosis, and marked folliculotropism, leading to follicular disruption. Cohesive groups of CD30+ large, atypical lymphocytes with a high proliferative index were seen focally. The patient was followed up for 41 months, during which time no relapses occurred.

Conclusions:

This case shows that PC-ALCL may present with different histologic features, including a follicular variant, that may mimic both benign and malignant conditions.

Childhood cutaneous lymphoid hyperplasia following feline scratches

Cutaneous lymphoid hyperplasia or pseudolymphoma is a usually benign inflammatory response that mimics lymphoma. Stimulation from foreign antigens introduced into the skin can induce this response. Scratches from pets are an effective mode of transmitting infections and inoculating foreign antigens into the skin. We report an unusual case of a child where cutaneous lymphoid hyperplasia presented as subcutaneous nodules at sites scratched by a pet cat.

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.

Cutaneous pseudolymphoma: an unusual presentation of a scalp mass

The term cutaneous pseudolymphoma (CPL), an accumulation of lymphocytes in response to a foreign antigen or unknown stimuli lacks specificity, and has been used when neither cause nor mechanism for the lymphocytic proliferation has been identified. Cases of childhood CPL are rare and require extensive investigation because of their potential for malignant transformation. We report a case of a child with a scalp mass diagnosed as CPL.

Primary cutaneous CD5+ marginal zone B-cell lymphoma resembling the plasma cell variant of Castleman's disease. Case report

Marginal zone B-cell lymphoma (MZBL) is occasionally associated with prominent plasma cell differentiation. However, MZBL rarely exhibits histological features that resemble plasmacytoma arising from a localized plasma cell variant of Castleman's disease (PCCD). We here report a histologically similar case that was associated with primary cutaneous tumor. The patient was a 57-year-old woman with a 5-year history of cutaneous nodules. Histologically, a prominent proliferation of plasma cells occupied the interfollicular area of the central portion of the cutaneous tumor, whereas various numbers of CD5+ centrocyte-like (CCL) cells, which were arranged in a marginal zone distribution pattern, occupied the peripheral region of the tumor. The majority of the lymphoid follicles had atrophic or regressive germinal centers resembling hyaline-vascular Castleman's disease. CCL cells were observed to have colonized a few of the lymphoid follicles. Immunohistochemistry revealed that these cells had a monotypic intracytoplasmic kappa chain. Without treatment, the patient was quiescent, but 2 years later, there was a transformation to the large cell type. These observations suggest that MZBL needs to be distinguished from PCCD, and that untreated cutaneous MZBL may undergo a high-grade blastic transformation similar to other indolent lymphoproliferative disorders.

Reactive lymphoid hyperplasia of the liver in a patient with colon cancer: report of two cases

BACKGROUND

Reactive lymphoid hyperplasia (RLH) of the liver is very rarely reported, and we encountered two cases of RLH of the liver in a patient with colon cancer.

CASE PRESENTATION

In the first case, a 77-year-old woman was admitted for the surgical removal of a ascending colon cancer. A hepatic tumor in the left lobe was concurrently revealed by computed tomography (CT), and magnetic resonance imaging (MRI). The appearance suggested liver metastasis. Right hemicolectomy and partial hepatectomy were performed. On histopathological examination, lymphoid follicles with germinal centers were seen in the tumor-like lesion, and remarkable lymphoid infiltration with germinal centers was seen in the portal area around the nodule. Immunohistochemical studies revealed polyclonality of infiltrating lymphocyte. Consequently, this nodular lesion was diagnosed as RLH of the liver. In the second case, a 64-year-old woman who had a radical right hemicolectomy for stage II ascending colon cancer 10 years ago was admitted with dysuria. A hepatic tumor in the left lobe was concurrently revealed by CT and MRI, suggesting hepatocellular carcinoma. A left lateral segmentectomy was performed. Microscopically, this lesion revealed the almost same findings as the first case, so this nodular lesion was diagnosed as RLH of the liver.

CONCLUSION

Our two cases were the first report of RLH of the liver accompanying colon cancer. Because there are a very few cases, so it is not clear whether the malignancies were involved in the onset of RLH. But we believe that new factors involved in the onset mechanism of RLH may be identified by carefully monitoring the clinical course of our two patients.

The New World Health Organization–European Organization for Research and Treatment of Cancer Classification of Cutaneous Lymphomas

The WHO-EORTC classification of cutaneous lymphomas is a good start to unifying nomenclature, a necessity before coherent consensus diagnoses can be made. There are three provisional diagnoses in this new classification that are not covered in detail in this review because they are rare diseases that still require further study for definitive classification. Much remains to be elucidated about cutaneous lymphomas, but understanding of the major entities within the new classification is an important first step in understanding these diverse diseases.