Myelodysplasia Cutis

CONTEXT.—

Myelodysplasia cutis is an emerging concept in cutaneous neoplasia. Many of these cases were previously included under the umbrella of histiocytoid Sweet syndrome. However, with the advent of next-generation sequencing, cutaneous involvement by myelodysplastic syndrome is being increasingly recognized.

OBJECTIVE.—

To review histiocytoid Sweet syndrome and myelodysplasia cutis and discuss our current understanding of these entities. Additionally, to discuss how next-generation sequencing can be applied in the evaluation of cutaneous infiltrates of immature histiocytoid cells.

DATA SOURCES.—

The English-language literature from 2005 to 2023 on the topic of histiocytoid Sweet syndrome and myelodysplasia cutis was reviewed.

CONCLUSIONS.—

Biopsy specimens showing infiltrates of histiocytoid, immature myeloid cells may represent cutaneous involvement by myelodysplastic syndrome. Close clinical correlation is recommended in these cases. Recent studies suggest that next-generation sequencing is useful in separating myelodysplasia cutis from true histiocytoid Sweet syndrome. This distinction has important implications for patients.

Primary cutaneous T-cell lymphoma: a review of the most common entities with focus on recent updates

Cutaneous T-cell lymphomas are an heterogeneous group of uncommon lymphoid neoplasms that are challenging to diagnose and require close collaboration between dermatologists, pathologists and hematologists/oncologists. This article reviews the most common cutaneous T-cell lymphomas: mycosis fungoides (both classic and variant forms) as well as its leukemic counterpart Sézary syndrome, CD30+ T-cell lymphoproliferative disorders including the ever-expanding group of lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma, and primary cutaneous CD4+ small/medium lymphoproliferative disorder. We discuss the classic clinical and histopathologic features of these lymphomas and review how they can be distinguished from reactive entities. In particularly, updates to these diagnostic categories and current controversies in classification are highlighted. Moreover, we review the prognosis and treatment for each entity. These lymphomas exhibit variable prognosis, and therefore it is important to correctly classify atypical cutaneous T-cell infiltrates for appropriate patient treatment and prognosis. Cutaneous T-cell lymphomas are at the interface of several medical specialties; this review seeks to summarize key features of these lymphomas and highlight new and emerging insights into these lymphomas.

CD30 expression in cutaneous B-cell lymphomas

INTRODUCTION

CD30 expression has been infrequently described in cutaneous B-cell lymphomas (CBCLs). We examined CD30 expression in reactive lymphoid hyperplasia (RLH) and CBCL and correlated expression with clinicopathologic features.

METHODS

CD30 was examined in 82 CBCL patients and 10 RLH patients that had been evaluated in our cutaneous lymphoma clinics. The CBCL patients included: primary cutaneous follicle center lymphoma (PCFCL), Grade 1/2 systemic/nodal follicular lymphoma (SFL); primary cutaneous marginal zone lymphoma/lymphoproliferative disorder (PCMZL/LPD); systemic marginal zone lymphoma (SMZL); primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT); and extracutaneous/systemic diffuse large B-cell lymphoma (eDLBCL). We scored CD30 expression for intensity and extent and related CD30 expression to age at first diagnosis, sex, site of biopsy, clinical appearance, extracutaneous involvement, multiple cutaneous lesions, B-symptoms, lymphadenopathy, positive positron emission tomography/computed tomography (PET/CT), elevated lactate dehydrogenase (LDH), and positive bone marrow biopsy.

RESULTS

CD30 expression was identified in 35% of CBCL, ranging from few, weak, scattered cells to strong and diffuse expression. It was most common in PCFCL and was not expressed in PCDLBCL-LT. Rare PCFCL expressed strong, diffuse CD30. Some cases of PCMZL/LPD, SMZL, FL, and RLH showed scattered, strongly positive cells. CD30 expression in CBCL was associated with favorable clinical features: younger age, negative PET/CT, and an LDH within normal limits.

CONCLUSIONS

CD30 may be expressed in CBCL, possibly causing diagnostic confusion. CD30 expression was most commonly identified in PCFCL and is associated with favorable clinical features. In cases with strong and diffuse expression, CD30 could be a therapeutic target.

Primary cutaneous T-cell lymphoma: a review of the most common entities with focus on recent updates

Cutaneous T-cell lymphomas are an heterogeneous group of uncommon lymphoid neoplasms that are challenging to diagnose and require close collaboration between dermatologists, pathologists and hematologists/oncologists. This article reviews the most common cutaneous T-cell lymphomas: mycosis fungoides (both classic and variant forms) as well as its leukemic counterpart Sézary syndrome, CD30+ T-cell lymphoproliferative disorders including the ever-expanding group of lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma, and primary cutaneous CD4+ small/medium lymphoproliferative disorder. We discuss the classic clinical and histopathologic features of these lymphomas and review how they can be distinguished from reactive entities. In particularly, updates to these diagnostic categories and current controversies in classification are highlighted. Moreover, we review the prognosis and treatment for each entity. These lymphomas exhibit variable prognosis, and therefore it is important to correctly classify atypical cutaneous T-cell infiltrates for appropriate patient treatment and prognosis. Cutaneous T-cell lymphomas are at the interface of several medical specialties; this review seeks to summarize key features of these lymphomas and highlight new and emerging insights into these lymphomas.

Cutaneous B-cell lymphomas: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Approximately one-fourth of primary cutaneous lymphomas are B-cell derived and are generally classified into three distinct subgroups: primary cutaneous follicle center lymphoma (PCFCL), primary cutaneous marginal zone lymphoma (PCMZL), and primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT).

DIAGNOSIS

Diagnosis and disease classification is based on histopathologic review and immunohistochemical staining of an appropriate skin biopsy. Pathologic review and an appropriate staging evaluation are necessary to distinguish primary cutaneous B-cell lymphomas from systemic B-cell lymphomas with secondary skin involvement.

RISK-STRATIFICATION

Disease histopathology remains the most important prognostic determinant in primary cutaneous B-cell lymphomas. Both PCFCL and PCMZL are indolent lymphomas that infrequently disseminate to extracutaneous sites and are associated with 5-year survival rates that exceed 95%. In contrast, PCDLBCL, LT is an aggressive lymphoma with an inferior prognosis.

RISK-ADAPTED THERAPY

PCFCL and PCMZL patients with solitary or relatively few skin lesions may be effectively managed with local radiation therapy. While single-agent rituximab may be employed for patients with more widespread skin involvement, multiagent chemotherapy is rarely appropriate. In contrast, management of patients with PCDLBCL, LT is comparable to the management of patients with systemic DLBCL.

Cutaneous T-cell lymphomas: 2023 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or the blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Two cases of challenging cutaneous lymphoid infiltrates presenting in the context of COVID-19 vaccination: A reactive lymphomatoid papulosis-like eruption and a bona fide lymphoma

COVID-19 infection and vaccination may be associated with a wide variety of cutaneous and immune manifestations. Here, we describe two patients who presented with monoclonal cutaneous T-cell infiltrates that showed cytologic and immunophenotypic features concerning for lymphoma shortly following COVID-19 vaccination. In one case, the eruption completely resolved. The second patient showed initial resolution, but her disease recurred and progressed following a breakthrough SARS-CoV-2 infection. These cases suggest that immune stimulation following exposure to SARS-Cov-2 protein(s) in vaccine or infection may facilitate the development of a lymphoma or lymphoproliferative disorder in susceptible individuals. Moreover, they show that separating these cases from pseudolymphomatous reactive conditions is often challenging and requires close clinical correlation.

Predictors of large cell transformation in patients with Sezary Syndrome-A retrospective analysis

BACKGROUND

Large cell transformation (LCT) of Sezary Syndrome (SS) is a rare phenomenon. To date, there are no rigorous studies identifying risk factors for its development.

OBJECTIVES

Here, we seek to characterize the clinicopathologic risk factors that predispose patients with SS to develop LCT.

METHODS

We retrospectively evaluated all SS patient records available in the Michigan Medicine Cancer Registry from 2010-2021. Clinical and pathologic variables were compared between groups. The Kaplan-Meier method and log-rank test were used to assess overall survival.

RESULTS

Of 28 SS patients identified, eight patients experienced LCT, and 20 did not (NLCT). Peak lactate dehydrogenase (LDH) before LCT (p = 0.0012), maximum total body surface area (TBSA) involvement before LCT (p = 0.0114), absolute CD8+ cell count measured on flow cytometry at diagnosis of SS (p = 0.0455) and at the most recent blood draw (p = 0.00736), and ulceration on biopsy (p = 0.0034) were significant clinicopathologic variables identified between the SS patients that developed LCT versus those that did not.

CONCLUSIONS

Maximum TBSA involvement, peak LDH, presence of ulceration, and decreased levels of CD8+ cells in the peripheral blood may predict the development of LCT in patients with SS.

GATA-3 is a proto-oncogene in T-cell lymphoproliferative neoplasms

Neoplasms originating from thymic T-cell progenitors and post-thymic mature T-cell subsets account for a minority of lymphoproliferative neoplasms. These T-cell derived neoplasms, while molecularly and genetically heterogeneous, exploit transcription factors and signaling pathways that are critically important in normal T-cell biology, including those implicated in antigen-, costimulatory-, and cytokine-receptor signaling. The transcription factor GATA-3 regulates the growth and proliferation of both immature and mature T cells and has recently been implicated in T-cell neoplasms, including the most common mature T-cell lymphoma observed in much of the Western world. Here we show that GATA-3 is a proto-oncogene across the spectrum of T-cell neoplasms, including those derived from T-cell progenitors and their mature progeny, and further define the transcriptional programs that are GATA-3 dependent, which include therapeutically targetable gene products. The discovery that p300-dependent acetylation regulates GATA-3 mediated transcription by attenuating DNA binding has novel therapeutic implications. As most patients afflicted with GATA-3 driven T-cell neoplasms will succumb to their disease within a few years of diagnosis, these findings suggest opportunities to improve outcomes for these patients.

Appropriate use criteria for ancillary diagnostic testing in dermatopathology: New recommendations for 11 tests and 220 clinical scenarios from the American Society of Dermatopathology Appropriate Use Criteria Committee

BACKGROUND

Appropriate use criteria (AUC) provide patient-centered physician guidance in test selection. An initial set of AUC was reported by the American Society of Dermatopathology (ASDP) in 2018. AUC reflect evidence collected at single timepoints and may be affected by evolving evidence and experience. The objective of this study was to update and expand AUC for selected tests.

METHODS

RAND/UCLA (RAND Corporation [Santa Monica, CA]/University of California Los Angeles) methodology used includes the following: (a) literature review; (b) review of previously rated tests and previously employed clinical scenarios; (c) selection of previously rated tests for new ratings; (d) development of new clinical scenarios; (e) selection of additional tests; (f) three rating rounds with feedback and group discussion after rounds 1 and 2.

RESULTS

For 220 clinical scenarios comprising lymphoproliferative (light chain clonality), melanocytic (comparative genomic hybridization, fluorescence in situ hybridization, reverse transcription polymerase chain reaction, telomerase reverse transcriptase promoter), vascular disorders (MYC), and inflammatory dermatoses (periodic acid-Schiff, Gömöri methenamine silver), consensus by panel raters was reached in 172 of 220 (78%) scenarios, with 103 of 148 (70%) rated "usually appropriate" or "rarely appropriate" and 45 of 148 (30%), "appropriateness uncertain."

LIMITATIONS

The study design only measures appropriateness. Cost, availability, test comparison, and additional clinical considerations are not measured. The possibility that the findings of this study may be influenced by the inherent biases of the dermatopathologists involved in the study cannot be excluded.

CONCLUSIONS

AUC are reported for selected diagnostic tests in clinical scenarios that occur in dermatopathology practice. Adhering to AUC may reduce inappropriate test utilization and improve healthcare delivery.

Patch/plaque mycosis-fungoides-like presentations of DUSP22-translocated T-cell lymphomas

The DUSP22-IRF4 gene rearrangement results in downregulation of DUSP22, a presumed tumor suppressor in T-cell lymphomagenesis. It has been described in some cases of primary cutaneous and systemic anaplastic large-cell lymphoma, lymphomatoid papulosis, and transformed mycosis fungoides. Here we describe two patients with clinical lesions resembling patch/plaque mycosis fungoides that did not meet WHO criteria for large-cell transformation on histopathology yet showed a DUSP22 translocation. One patient who had a history of systemic anaplastic large-cell lymphoma with DUSP22 translocation presented with cutaneous involvement by his systemic lymphoma along with lymphomatoid papulosis and mycosis-fungoides-like lesions, all showing an identical immunophenotype and T-cell clone. These cases expand the spectrum of DUSP22-rearranged lymphomas to include mycosis-fungoides-like presentations without large-cell transformation.

Cutaneous T-cell lymphomas: 2021 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies, including biologic-response modifiers, histone deacetylase inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Dermoscopic Features of Mycosis Fungoides and Its Variants in Patients with Skin of Color: A Retrospective Analysis

Background

Mycosis fungoides (MF) is a cutaneous T-cell lymphoma that disproportionately affects people with skin of color and is difficult to diagnose.

Objective

This study characterized the dermoscopic features of MF and its subtypes in patients with skin of color.

Methods

Dermoscopic images of patients with skin of color seen at the cutaneous T-cell lymphoma clinic at Michigan Medicine Dermatology between 2018 and 2019 were reviewed. Specific dermoscopic features were identified and summarized for each subtype of MF.

Results

A total of 33 dermoscopic images from 11 patients with skin of color were reviewed. Four patients had classic MF (18 dermoscopic images), 4 had hypopigmented MF (9 dermoscopic images), 1 had folliculotropic MF (4 dermoscopic images), and 2 had verrucous MF (2 dermoscopic images). Classic MF was characterized by striking pigmentary change, thick black lines, white rosettes, and geometric white lines. Hypopigmented MF was characterized by the loss of the patient's natural pigment network. In folliculotropic MF, follicular plugging and hyperpigmented to violaceous perifollicular halos were observed. In verrucous MF, large, yellow-gray amorphous structures with yellow-gray ridges and comedo-like openings were observed within hyperkeratotic areas. Overall, vessel morphology was difficult to discern on dermoscopy.

Conclusions

Dermoscopic features of MF in patients with skin of color are predominantly characterized by striking pigmentary alteration. Vessel morphology is not a reliable diagnostic feature. As patients with MF and skin of color have a worse prognosis than light-skinned individuals, a better understanding of dermoscopic features may aid in early diagnosis and improve outcomes in this group.

Immunophenotypic switch in cutaneous T-cell lymphoma: A series of three cases and review of the literature

Primary cutaneous T-cell lymphoma (CTCL) comprises a heterogeneous group of neoplasms with variable clinical behavior. Immunophenotypic switch (IS) is a phenomenon that occurs during lymphoma progression and is defined by an alteration in the immunophenotypic expression of a tumor with retention of its genotypic signature. This has been well-recognized in hematopoietic neoplasms; however, it has been rarely reported in CTCL and its clinical implications are not well understood. We present the clinical, histopathologic, immunophenotypic, and genetic findings of three cases of CTCL that demonstrated IS post treatment with variable outcomes. We add our cases to the small number previously reported to increase awareness of this phenomenon and its diagnostic challenge.

Primary cutaneous follicle center lymphoma with extensive plasmacytic differentiation and t(14;18) in both the lymphoid and plasma cell components

Primary cutaneous follicle center lymphoma (PCFCL) is the most common cutaneous B-cell lymphoma. The typical immunophenotype includes expression of both CD20 and BCL6, with the majority of cases lacking expression of CD10, BCL2, and the characteristic t(14;18)/IGH-BCL2 rearrangement seen in systemic follicular lymphoma (FL). Plasmacytic differentiation (PD) is an uncommon finding in both systemic and cutaneous FLs and presents a diagnostic challenge when present, leading to the potential for misdiagnosis as marginal zone lymphoma (MZL). Limited reports have described light chain restriction in the plasma cell component of FLs with PD, and rare cases of PCFCL with PD have been described. While the IGH-BCL2 translocation has been identified in a subset of FLs with PD, the presence of the BCL2 translocation in monotypic plasma cells of PCFCL has not been previously described to our knowledge. Here, we report a case of PCFCL with extensive PD in a 77-year-old woman that was favored to represent primary cutaneous MZL on an initial punch biopsy. Excisional biopsy, however, revealed that the atypical lymphocytes expressed CD10, BCL6, and BCL2, while the plasma cell component demonstrated light-chain lambda restriction. FISH studies showed the presence of an IGH-BCL2 translocation in both the lymphocytic and plasmacytic components.

Cutaneous follicle center lymphomas with plasmacytic differentiation

Follicle center lymphomas, including primary cutaneous follicle center lymphoma (PCFCL), may rarely show plasmacytic differentiation. Such cases can pose a diagnostic challenge and can be mistaken for other lymphomas that more commonly include plasma cells. Here, we report four cases of PCFCL and one case of systemic follicular lymphoma involving the skin with associated monotypic plasma cells, including the clinical, morphologic and immunophenotypic features.

Cutaneous B-cell lymphomas: 2021 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Approximately one-fourth of primary cutaneous lymphomas are B-cell derived and are generally classified into three distinct subgroups: primary cutaneous follicle center lymphoma (PCFCL), primary cutaneous marginal zone lymphoma (PCMZL), and primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT).

DIAGNOSIS

Diagnosis and disease classification is based on histopathologic review and immunohistochemical staining of an appropriate skin biopsy. Pathologic review and an appropriate staging evaluation are necessary to distinguish primary cutaneous B-cell lymphomas from systemic B-cell lymphomas with secondary skin involvement.

RISK-STRATIFICATION

Disease histopathology remains the most important prognostic determinant in primary cutaneous B-cell lymphomas. Both PCFCL and PCMZL are indolent lymphomas that infrequently disseminate to extracutaneous sites and are associated with 5-year survival rates that exceed 95%. In contrast, PCDLBCL, LT is an aggressive lymphoma with an inferior prognosis.

RISK-ADAPTED THERAPY

Both PCFCL and PCMZL patients with solitary or relatively few skin lesions may be effectively managed with local radiation therapy. While single-agent rituximab may be employed for patients with more widespread skin involvement, multi-agent chemotherapy is rarely appropriate. In contrast, management of patients with PCDLBCL, LT is comparable to the management of patients with systemic DLBCL.

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.

Mycosis fungoides and Sézary syndrome: 2019 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas (CTCL) are a heterogenous group of T-cell neoplasms involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, skin-directed therapies are preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with systemic therapies. These include biologic-response modifiers, histone deacetylase (HDAC) inhibitors, or antibody-based strategies, in an escalating fashion. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Primary Cutaneous Follicle Center Lymphoma

CONTEXT.—

Primary cutaneous follicle center lymphoma is a low-grade B-cell lymphoma that is limited to the skin at diagnosis. It has a differential diagnosis that includes systemic/nodal follicular lymphoma secondarily involving the skin; primary cutaneous diffuse large B-cell lymphoma leg type; reactive lymphoid hyperplasia; and primary cutaneous marginal zone lymphoma.

OBJECTIVE.—

To review the clinical, morphologic, immunophenotypic, and genetic features of primary cutaneous follicle center lymphoma; its differential diagnosis; and the evidence that supports use of immunohistochemistry and genetic testing in the diagnosis and prognosis of this entity.

DATA SOURCES.—

Pertinent literature regarding cutaneous B-cell lymphomas is summarized and University of Michigan cases are used to highlight characteristics of primary cutaneous follicle center lymphoma.

CONCLUSIONS.—

Primary cutaneous follicle center lymphoma is a low-grade B-cell lymphoma with distinctive features, although some cases may have elements that overlap with other lymphomas, complicating interpretation.

Merkel cell carcinoma arising in association with cutaneous T-cell lymphoma: A potential diagnostic pitfall

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous neuroendocrine carcinoma with increased prevalence in patients with immunosuppression or B-cell neoplasms. To the best of our knowledge, an association with cutaneous T-cell lymphoma (CTCL) has not been previously described. In this report, we present two cases of MCC arising in the setting of CTCL. The first case was a female during her 70s with previously diagnosed stage IVA1 Sezary syndrome. Biopsy of a scaly patch showed two distinct abnormal cell populations. The first population consisted of hyperchromatic dermal and epidermotropic lymphocytes, expressing CD3 and CD4 with diminished CD7. The second population consisted of intraepidermal clusters of larger atypical cells that expressed synaptophysin, neurofilament, CK20, and Merkel cell polyomavirus transcript. The combination of findings was consistent with intraepidermal MCC in a background of CTCL. Excision showed residual intraepidermal MCC without dermal involvement. The second case was a male during his 50s with a longstanding history of mycosis fungoides, who presented with a new lesion on his right thigh. Biopsy and excision showed dermal MCC without secondary involvement by CTCL. Our cases show that MCC may rarely occur in the setting of T-cell lymphoma, and that intraepidermal MCC may mimic epidermotropic T-cells.

Molecular testing of borderline cutaneous melanocytic lesions: SNP array is more sensitive and specific than FISH

Melanocytic lesions with borderline features are diagnostically challenging. Single-nucleotide polymorphism (SNP) arrays, which detect genomic copy number alterations (CNAs), can be helpful in distinguishing between nevi and melanoma. Fluorescence in situ hybridization (FISH) has been used as a more rapid, less expensive alternative to SNP array, using a panel of probes that are often gained or lost in melanoma. We used SNP array data from 63 borderline cutaneous melanocytic lesions and 44 definitive melanomas to predict the performance of FISH testing. Lesions were considered positive by "virtual FISH" if 1 or more of the 5 FISH-probed loci demonstrated appropriate CNAs by SNP array. Cases were classified as positive by SNP array if ≥3 CNAs were present, based on internal validation studies, or if FISH criteria were met. Conventional FISH was performed in 33 cases (17 borderline lesions, 16 melanomas). Of the 63 borderline cases, 44 (70%) were positive by SNP array and 30 (48%) were positive by virtual FISH. A higher proportion of melanomas were positive by SNP array (41/44, 93% sensitivity) and virtual FISH (36/44, 82% sensitivity). Virtual FISH had 61% sensitivity in the borderline group using SNP array as the gold standard, whereas specificity was 84%. There was good correlation between conventional and virtual FISH, with agreement in 30 of 33 (91%) cases. Although FISH is highly effective in distinguishing between nevi and melanoma in cases where the histological diagnosis is straightforward, it is not nearly as sensitive or specific as SNP array when applied to borderline lesions.

Primary Cutaneous Composite Lymphomas

Composite lymphomas have been defined as 2 distinct subtypes of lymphoma occurring at a single anatomic site. Composite lymphomas limited to the skin are a rare occurrence and pose a unique challenge. Many reported cases within the skin are combined B-cell and T-cell lymphomas, typically mycosis fungoides and a low-grade B-cell lymphoma. These cases are challenging to recognize because lymphoid infiltrates within the skin often include a mixed population of B cells and T cells. In particular, reactive lymphoid proliferations (pseudolymphomas), primary cutaneous low-grade B-cell lymphomas, and primary cutaneous CD4+ T-cell lymphoproliferative disorder may show nearly equal numbers of B cells and T cells. In order to exclude these possibilities, overwhelming evidence in support of each lymphoma is helpful, including abnormal architecture, cytology, and immunophenotype, as well as molecular genetic evidence of clonality.

Polo-like-kinase 1 (PLK-1) and c-myc inhibition with the dual kinase-bromodomain inhibitor volasertib in aggressive lymphomas

Survival following anthracycline-based chemotherapy remains poor among patients with most T-cell lymphoproliferative disorders. This may be attributed, at least in part, to cell-autonomous mechanisms of chemotherapy resistance observed in these lymphomas, including the loss of important tumor suppressors and the activation of signaling cascades that culminate in the expression and activation of transcription factors promoting cell growth and survival. Therefore, the identification of novel therapeutic targets is needed. In an effort to identify novel tumor dependencies, we performed a loss-of-function screen targeting ≈500 kinases and identified polo-like kinase 1 (PLK-1). This kinase has been implicated in the molecular cross-talk with important oncogenes, including c-Myc, which is itself an attractive therapeutic target in subsets of T-cell lymphomas and in high-grade (“double hit”) diffuse large B-cell lymphomas. We demonstrate that PLK-1 expression is prevalent among these aggressive lymphomas and associated with c-myc expression. Importantly, PLK-1 inhibtion with the PLK-1 inhibitor volasertib significantly reduced downstream c-myc phosphorylation and impaired BRD4 binding to the c-myc gene, thus inhibiting c-myc transcription. Therefore, volasertib led to a nearly complete loss of c-myc expression in cell lines and tumor xenografts, induced apoptosis, and thus warrants further investigation in these aggressive lymphomas.

A single center phase II study of ixazomib in patients with relapsed or refractory cutaneous or peripheral T-cell lymphomas

The transcription factor GATA-3, highly expressed in many cutaneous T-cell lymphoma (CTCL) and peripheral T-cell lymphomas (PTCL), confers resistance to chemotherapy in a cell-autonomous manner. As GATA-3 is transcriptionally regulated by NF-κB, we sought to determine the extent to which proteasomal inhibition impairs NF-κB activation and GATA-3 expression and cell viability in malignant T cells. Proteasome inhibition, NF-κB activity, GATA-3 expression, and cell viability were examined in patient-derived cell lines and primary T-cell lymphoma specimens ex vivo treated with the oral proteasome inhibitor ixazomib. Significant reductions in cell viability, NF-κB activation, and GATA-3 expression were observed preclinically in ixazomib-treated cells. Therefore, an investigator-initiated, single-center, phase II study with this agent in patients with relapsed/refractory CTCL/PTCL was conducted. Concordant with our preclinical observations, a significant reduction in NF-κB activation and GATA-3 expression was observed in an exceptional responder following one month of treatment with ixazomib. While ixazomib had limited activity in this small and heterogeneous cohort of patients, inhibition of the NF-κB/GATA-3 axis in a single exceptional responder suggests that ixazomib may have utility in appropriately selected patients or in combination with other agents.

Primary Cutaneous Acral CD8+ T-Cell Lymphoma

Primary cutaneous acral CD8+ T-cell lymphoma is a new provisional entity in the 2016 revision of the World Health Organization classification of lymphoid neoplasms. This is a challenging diagnosis because of its rarity, as well as its morphologic and immunophenotypic overlap with other CD8+ cytotoxic lymphoid proliferations. Appropriate classification of this entity is crucial because of its indolent clinical behavior compared with other CD8+ T-cell lymphomas. Knowledge of the clinical setting, sites of involvement, and morphologic features can aid in correct diagnosis. Here, we review the clinical and pathologic features of primary cutaneous acral CD8+ T-cell lymphoma with an emphasis on the differential diagnosis among other C8+ T-cell lymphomas.

Unsuspected lymphomatoid granulomatosis in a patient with antisynthetase syndrome

Clinical diagnosis of lymphomatoid granulomatosis (LYG) often is difficult, especially in patients with multiple comorbidities. We present a 60-year-old woman with worsening fatigue, night sweats, unintentional weight loss, and dyspnea of 2 weeks' duration. Her medical history was remarkable for recent radiation therapy for recurrent breast cancer and antisynthetase syndrome complicated by interstitial lung disease and controlled with azathioprine. Computed tomography showed ground-glass opacities and nodular infiltrates in all lung lobes, raising concern for radiation pneumonitis and drug toxicity. Skin examination revealed erythematous and hemorrhagic papules, macules, and blisters on the lower leg. A diagnosis of LYG was made on a skin biopsy showing large angiocentric Epstein-Barr virus (EBV)-positive B cells. The patient soon progressed to develop nodal large B-cell lymphoma and died 6 weeks later. This rare report of LYG in a patient with antisynthetase syndrome highlights the diagnostic difficulty and aggressive course of LYG as well as the important role of skin biopsy in establishing the diagnosis.

A retrospective comparative outcome analysis following systemic therapy in Mycosis fungoides and Sezary syndrome

Cutaneous T-cell lymphomas (CTCL), with few exceptions, remain incurable and treatment is largely palliative. We performed a retrospective analysis of systemic treatment outcomes of patients diagnosed with MF/SS. We identified 223 patients with MF/SS evaluated at a single institution from 1997 to 2013. Disease stage at diagnosis, time of treatment, and treatments received were retrospectively analyzed using our CTCL database. The primary endpoint was time to next treatment (TTNT). Treatment outcomes were analyzed using Kaplan-Meier method and comparisons among groups were made using log-rank analysis. A superior TTNT was associated with retinoid or interferon therapies when compared with HDAC inhibitors or systemic chemotherapy. Retinoids and interferon were associated with superior TTNT in both limited-stage and advanced stage disease. Extracorporeal photophoresis (ECP) had a superior TTNT in Sezary Syndrome. HDAC inhibitors and chemotherapy were associated with inferior TTNT in both limited stage disease and advanced stage disease. With the exception of interferon, retinoids, or ECP, durable responses are rarely achieved with systemic therapies in MF/SS patients, particularly those with advanced-stage disease. Therefore, clinical trial participation with novel agents should be encouraged. Am. J. Hematol. 91:E491-E495, 2016. © 2016 Wiley Periodicals, Inc.

Protein gene product 9.5 (PGP9.5) expression in benign cutaneous mesenchymal, histiocytic, and melanocytic lesions: comparison with cellular neurothekeoma

Cellular neurothekeoma (CNTK) frequently enters the differential diagnosis of a benign dermal cellular proliferation. Diagnosis often relies on immunohistochemistry including the use of protein gene product 9.5 (PGP9.5). A previous study demonstrated PGP9.5 expression across a wide variety of soft tissue neoplasms. We explored the utility of this antibody in distinguishing CNTK from other benign dermal-based lesions. A cohort of CNTK (n=7) and benign cutaneous lesions of neural (n=28), fibrohistiocytic (n=23), fibroblastic (n=25), histiocytic (n=18), myofibroblastic (n=7), smooth muscle (n=14), and melanocytic (n=12) differentiations were immunostained with PGP9.5. Staining was graded by H-score and compared with CNTK. A significantly higher H-score was found in CNTK compared with the fibrohistiocytic (p=0.0001), histiocytic (p=0.0016), myofibroblastic (p=0.0003), smooth muscle (p<0.0001), and melanocytic (p=0.0004) groups, with the exceptions of plexiform fibrohistiocytic tumour, xanthoma, and xanthogranuloma. No significant difference was found when comparing CNTK with fibroblastic and neural lesions, with the exceptions of neurofibroma and perineurioma. In conclusion, PGP9.5 is helpful in distinguishing CNTK from most benign cutaneous fibrohistiocytic, histiocytic, myofibroblastic, smooth muscle, and melanocytic lesions. In addition to CNTK and neural lesions, PGP9.5 is also expressed in benign fibroblastic lesions, and therefore distinction of these lesions should not be based on PGP9.5 positivity.

T-cell Receptor Signaling Activates an ITK/NF-κB/GATA-3 axis in T-cell Lymphomas Facilitating Resistance to Chemotherapy

Purpose: T-cell lymphomas are a molecularly heterogeneous group of non-Hodgkin lymphomas (NHL) that account for a disproportionate number of NHL disease-related deaths due to their inherent and acquired resistance to standard multiagent chemotherapy regimens. Despite their molecular heterogeneity and frequent loss of various T cell-specific receptors, the T-cell antigen receptor is retained in the majority of these lymphomas. As T-cell receptor (TCR) engagement activates a number of signaling pathways and transcription factors that regulate T-cell growth and survival, we examined the TCR's role in mediating resistance to chemotherapy.Experimental Design: Genetic and pharmacologic strategies were utilized to determine the contribution of tyrosine kinases and transcription factors activated in conventional T cells following TCR engagement in acquired chemotherapy resistance in primary T-cell lymphoma cells and patient-derived cell lines.Results: Here, we report that TCR signaling activates a signaling axis that includes ITK, NF-κB, and GATA-3 and promotes chemotherapy resistance.Conclusions: These observations have significant therapeutic implications, as pharmacologic inhibition of ITK prevented the activation of this signaling axis and overcame chemotherapy resistance. Clin Cancer Res; 23(10); 2506-15. ©2016 AACR.

Subcutaneous panniculitis-like T-cell lymphoma with bone marrow involvement

OBJECTIVES

To describe a rare case of subcutaneous panniculitis-like T-cell lymphoma (SPTCL) with morphologic and immunophenotypic evidence of bone marrow involvement.

METHODS

Biopsy specimens of skin and subcutis and bone marrow were examined using H&E-stained sections. Immunohistochemical studies for CD2, CD3, CD4, CD5, CD7, CD8, CD20, CD30, CD56, and granzyme B were reviewed. In addition, T-cell receptor γ gene rearrangement studies were performed.

RESULTS

A bone marrow core biopsy demonstrated several lymphohistiocytic aggregates containing atypical, cytotoxic T cells that rimmed adipocytes and were associated with karyorrhexis. These T cells were morphologically and immunophenotypically identical to a concurrent SPTCL, expressing CD2, CD3, CD7, CD8, and granzyme B but with diminished CD5 expression.

CONCLUSIONS

SPTCL may rarely involve the bone marrow. Bone marrow infiltrates show a similar morphologic and immunophenotypic appearance to those in the subcutaneous fibroadipose tissue, including rimming of adipocytes by neoplastic lymphocytes.

Selected Inflammatory Imitators of Mycosis Fungoides: Histologic Features and Utility of Ancillary Studies

Mycosis fungoides is the most common primary cutaneous lymphoma; however, it remains a significant diagnostic challenge, in part because of the overlap with several inflammatory dermatoses. Despite advances in immunohistochemistry and molecular diagnostics, false-positive, false-negative, and indeterminate diagnoses are not uncommon. In most cases, the overall balance of morphologic, immunophenotypic, and genetic features must be considered carefully because there are few sensitive and specific clues to the diagnosis. Moreover, an appropriate clinical presentation is essential to the diagnosis and helps to favor or exclude inflammatory/reactive processes. Herein, we discuss 3 important inflammatory dermatoses that may closely simulate mycosis fungoides, and we review the use of ancillary studies in these challenging cases.

Controversies and Considerations in the Diagnosis of Primary Cutaneous CD4+ Small/Medium T-Cell Lymphoma

Context.—Primary cutaneous CD4+ small/medium T-cell lymphoma is a provisional and controversial entity with a broad differential diagnosis. Despite being an uncommon lymphoma, it is a frequent diagnostic consideration in cutaneous biopsies with a dense lymphoid infiltrate because it shows overlapping features with reactive lymphoid hyperplasia (pseudolymphoma) and a variety of other primary cutaneous and systemic lymphomas. However, proper classification of this process is important for determining patient prognosis and treatment options.

Objective.—To review the clinical, morphologic, immunophenotypic, and genetic features of primary cutaneous CD4+ small/medium T-cell lymphoma and contrast those features with entities in the differential diagnosis.

Data Sources.—Applicable literature will be reviewed with emphasis on current controversies and distinguishing characteristics.

Conclusions.—Although many consider primary cutaneous CD4+ small/medium T-cell lymphoma to be indistinguishable from reactive lymphoid hyperplasia/pseudolymphoma, it can be differentiated from other primary cutaneous and systemic lymphomas. Patients with solitary lesions of primary cutaneous CD4+ small/medium T-cell lymphoma generally have an excellent prognosis. Nevertheless, a subset of patients who have been reported to meet criteria for this lymphoma have followed a more-aggressive course; however, those patients show some differing clinical, morphologic, and immunophenotypic features.

Inactivation of the Cdkn2a locus cooperates with HMGA1 to drive T-cell leukemogenesis

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive leukemia with high relapse rates compared to B-lineage ALL. We previously showed that HMGA1a transgenic mice develop aggressive T-ALL, indicating that HMGA1 causes leukemic transformation in vivo. HMGA1 is also highly expressed in embryonic stem cells, hematopoietic stem cells and diverse, refractory human cancers. Disruption of the CDKN2A tumor suppressor locus occurs in most cases of T-ALL and is thought to contribute to leukemic transformation. To determine whether loss of function of CDKN2A cooperates with HMGA1 in T-ALL, we crossed HMGA1a transgenics onto a Cdkn2a null background. We discovered that T-ALL is markedly accelerated in HMGA1a transgenic Cdkn2a null mice. In addition, these mice recapitulate salient clinical and pathologic features of human T-ALL. HMGA1 is also highly overexpressed in human T-ALL. These findings suggest that HMGA1 plays a causative role in T-ALL and could represent a rational therapeutic target.

Primary cutaneous diffuse large B-cell lymphoma, leg type: diagnostic considerations

CONTEXT

Primary cutaneous diffuse large B-cell lymphoma, leg type, may show features that overlap with other lymphomas. However, timely recognition of this entity can have important clinical and therapeutic implications.

OBJECTIVE

To review the clinical, morphologic, and immunophenotypic characteristics of primary cutaneous diffuse large B-cell lymphoma, leg type, and juxtapose these features with other diagnostic considerations. In particular, other variants of primary cutaneous diffuse large B-cell lymphoma, as well as primary cutaneous follicle center lymphoma, will be reviewed. Additionally, systemic/extracutaneous lymphomas will be discussed, including diffuse large B-cell lymphoma, not otherwise specified, Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly, and lymphomatoid granulomatosis.

DATA SOURCES

Relevant literature will be reviewed and key differentiating findings will be highlighted.

CONCLUSIONS

Although primary cutaneous diffuse large B-cell lymphoma, leg type, may show aspects that overlap with other lymphomas, it can be distinguished from other entities in the differential diagnosis.

A "high-risk" epithelioid hemangioendothelioma presenting as a solitary, ulcerated, subcutaneous tumor

So-called "high-risk" epithelioid hemangioendotheliomas are uncommon neoplasms that demonstrate classic histopathologic features of epithelioid hemangioendotheliomas and a size larger than 3 cm or >3 mitotic figures per 50 high power fields. These neoplasms show an increased rate of metastasis (25% of cases) and are associated with a poor 5-year survival (59%). They may pose a diagnostic challenge for dermatopathologists as they mimic metastatic carcinoma, malignant mixed tumor, melanocytic neoplasms, epithelioid sarcoma, and epithelioid angiosarcoma. High-risk epithelioid hemangioendothelioma has not been previously reported as a solitary ulcerated mass in the skin. Here, we describe one such lesion that developed as a rapidly growing ulcerative skin tumor in a 33-year-old African American man with a remote history of Burkitt lymphoma. We also review the evolution and controversies in the understanding and classification of this neoplasm.

Simplified flow cytometric assessment in mycosis fungoides and Sézary syndrome

By using flow cytometry with markers for CD3, CD4, CD26, and CD7, we examined the blood samples of 109 patients for abnormal T cells: 69 patients with mycosis fungoides (MF)/Sézary syndrome (SS), 31 hospitalized control subjects, and 9 patients with inflammatory skin disease. T cells were identified as quantitatively abnormal (>15% CD26- or CD7- T cells) or phenotypically abnormal (CD26- or CD7- T cells with bright or dim CD3 or CD4 or bright CD7). Patients were followed for a median of 82 months, and abnormal T cells were correlated with diagnosis, clinical outcome, and other laboratory parameters. Abnormal T-cell populations were identified in 46% of patients with MF/SS (32/69) and correlated with disease extent. Quantitative abnormalities were more frequent than phenotypic abnormalities, and CD4+/CD26- T cells were more frequent than CD4+/CD7- T cells. CD26- T cells correlated better with disease extent than did CD7 -. Increasing numbers of abnormal T cells were associated with worsening disease. Flow cytometry provides valuable information for diagnosis, prognosis, and therapeutic efficacy in MF/SS.