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.