John K.C. Chan

EML4-ALK Rearrangement in Non-Small Cell Lung Cancer and Non-Tumor Lung Tissues

A fusion gene, echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase (EML4-ALK), with transforming activity has recently been identified in a subset of non-small cell lung cancer (NSCLC), but its pathogenetic, diagnostic, and therapeutic roles remain unclear. Both frequency and type of EML4-ALK transcripts were investigated by reverse transcription PCR in 120 frozen NSCLC specimens from Italy and Spain; non-neoplastic lung tissues taken far from the tumor were used as controls. In cases carrying the fusion transcript, we determined EML4-ALK gene and protein levels using fluorescence in situ hybridization, Western blotting, and immunoprecipitation. We also analyzed ALK protein levels in paraffin samples from 662 NSCLC specimens, including the 120 cases investigated in the molecular studies. EML4-ALK transcripts (variants 1 and 3) were detected in 9 of 120 NSCLC samples but were not specific for NSCLC since they were also found in non-cancerous lung tissues taken far from the tumor. Notably, no transcripts were detected in matching tumor samples from these patients. Fluorescence in situ hybridization analysis of cases expressing EML4-ALK transcripts showed that only a minority of cells harbored the EML4-ALK gene. None of these cases was found to express the EML4-ALK protein as examined by immunohistochemistry, Western blotting, and immunoprecipitation. The EML4-ALK transcript cannot be regarded as a specific diagnostic tool for NSCLC. Our results show therefore that the causal role and value of EML4-ALK as a therapeutic target remain to be defined.

Angiomyofibroblastoma of the vulva. A benign neoplasm distinct from aggressive angiomyxoma.

Aggressive angiomyxoma of pelvic soft parts is a rare lesion with a high risk of recurrence. We report 10 cases of angiomyofibroblastoma, a hitherto uncharacterized benign tumor of the vulva histologically mimicking aggressive angiomyxoma. All patients had a vulval mass, often clinically diagnosed as a Bartholins cyst. There was no recurrence after excision. The tumors were well circumscribed, measuring 0.5–12 cm in maximum dimension. They were characterised by alternating hypercellular and hypocellular edematous zones in which abundant blood vessels (predominantly of the capillary type) were irregularly distributed. Spindled, plump spindled, and oval stromal cells were aggregated around the blood vessels. sometimes forming solid compact foci, or were loosely dispersed in the hypocellular areas. Their nuclei were bland, but rare ones were enlarged and hyperchromatic in four cases. Some cells had abundant eosinophilic hyaline cytoplasm and eccentrically placed nuclei. Mitotic figures were absent or very sparse. Scattered throughout were thin, wavy strands or thick bundles of collagen. Mast cells were readily seen in eight cases. Immunohistochemically, the stromal cells were reactive for vimentin and desmin, but not cytokeratin, muscle-specific actin, a-smooth muscle actin, or S-100 protein. Ultrastructural studies showed well-developed rough endoplasmic reticulum, Golgi apparatus, abundant intermediate filaments, and pinocytotic vesicles in the stromal cells. Angiomyofibroblastoma can be distinguished from aggressive angiomyxoma by its circumscribed borders, much higher cellularity, more numerous blood vessels (which lack prominent hyalinization), frequent presence of plump stromal cells, minimal stromal mucin, and rarity of erythrocyte extravasation.

Immunostaining for Thyroid Transcription Factor 1 and Cytokeratin 20 Aids the Distinction of Small Cell Carcinoma From Merkel Cell Carcinoma, But Not Pulmonary From Extrapulmonary Small Cell Carcinomas

OBJECTIVE To study the expression of thyroid transcription factor 1 (TTF-1) and cytokeratin 20 (CK20) in pulmonary small cell carcinomas, extrapulmonary small cell carcinomas, and Merkel cell carcinomas, and thereby determine whether these markers are helpful in distinguishing these 3 groups of small cell neuroendocrine carcinomas. MATERIALS AND METHODS Immunostaining for TTF-1 and CK20 was performed in 102 cases of small cell carcinoma (pulmonary, 52; extrapulmonary, 50) and 23 cases of Merkel cell carcinoma. The results for the 3 groups were compared. RESULTS Thyroid transcription factor 1 was expressed in 82.7% of pulmonary small cell carcinomas, 42.0% of extrapulmonary small cell carcinomas (range, 33.3--53.3% for the various sites), and 0% of Merkel cell carcinomas. Cytokeratin 20 staining was consistently negative in pulmonary small cell carcinomas, and positive in 4.0% of extrapulmonary small cell carcinomas and 100% of Merkel cell carcinomas. CONCLUSIONS Immunostaining for TTF-1, especially when combined with immunostaining for CK20, can aid in the distinction between Merkel cell carcinoma and small cell carcinoma (both pulmonary and extrapulmonary). However, in individual cases, these markers cannot be used to distinguish between pulmonary and extrapulmonary small cell carcinomas due to the extensive overlap in immunophenotypes.

Coordinated Silencing of MYC-Mediated miR-29 by HDAC3 and EZH2 as a Therapeutic Target of Histone Modification in Aggressive B-Cell Lymphomas

We investigated the transcriptional and epigenetic repression of miR-29 by MYC, HDAC3, and EZH2 in mantle cell lymphoma and other MYC-associated lymphomas. We demonstrate that miR-29 is repressed by MYC through a corepressor complex with HDAC3 and EZH2. MYC contributes to EZH2 upregulation via repression of the EZH2 targeting miR-26a, and EZH2 induces MYC via inhibition of the MYC targeting miR-494 to create positive feedback. Combined inhibition of HDAC3 and EZH2 cooperatively disrupted the MYC-EZH2-miR-29 axis, resulting in restoration of miR-29 expression, downregulation of miR-29-targeted genes, and lymphoma growth suppression in vitro and in vivo. These findings define a MYC-mediated miRNA repression mechanism, shed light on MYC lymphomagenesis mechanisms, and reveal promising therapeutic targets for aggressive B-cell malignancies.

sarcomatoid variant of anaplastic large-cell KI-1 lymphoma

Although anaplastic large-cell Ki-1 lymphomas can mimic a variety of tumors, a correct diagnosis is usually not difficult to reach if it is recognized that lymphoma cells can assume bizarre and pleomorphic appearances and that the pattern of growth can be purely sinusoidal. We report a unique case of a 45-year-old man presenting with a leg lesion that showed sarcomatoid growth patterns. The subcutaneous/dermal tumor displayed a myxoid stroma reminiscent of myxoid malignant fibrous histiocytoma. In a subsequent lymph node biopsy, a well-developed storiform pattern was formed by interweaving fascicles of plump spindle and oval neoplastic cells, reminiscent of pleomorphic/storiform type of malignant fibrous histiocytoma. The lymphoid nature of the tumor cells was documented by immunoreactivity for leukocyte common antigen, Ki-1 antigen, and the T-cell marker UCHL1. We conclude that the presence of a storiform or myxoid pattern does not disqualify the diagnosis of lymphoma; this possibility should always be pursued in pleomorphic tumors because the treatment is substantially different from that for sarcoma, carcinoma, or melanoma.

Expression of natural killer cell markers in non-Hodgkin's lymphomas

One hundred forty-nine cases of non-Hodgkins lymphoma were studied with a panel of monoclonal antibodies, including antibodies to natural killer (NK) cells--anti-NKH1, anti-Leu 7, and anti-Leu 11b. There were 95 B-cell, 51 T-cell, and three null cell lymphomas. Seventeen T-cell lymphomas (33 per cent) expressed NKH1, Leu 7, and/or Leu 11b. None of the B- or null cell lymphomas expressed the NK markers. In comparison with the NK-negative T-cell lymphomas, the NK-positive cases showed a predilection for the nasal and paranasal region. There was a more significant loss of the T-cell markers T3 (peripheral T cell) and T4 (T-helper cell) in NK-positive lymphomas. The difference was due to a high proportion of nasal/paranasal lymphomas, which were associated with a frequent loss of T-cell markers, among the NK-positive cases. However, a similar degree of loss of T-cell markers was observed among NK-positive and NK-negative nasal/paranasal lymphomas. We conclude that expression of NK markers occurs exclusively in a proportion of T-cell lymphomas, but not B-cell or null cell lymphomas. The reason this occurs predominantly in nasal and paranasal lymphomas is unknown.

Aggressive angiomyxoma. A report of four cases occurring in men.

Aggressive angiomyxoma is a distinctive, locally aggressive but nonmetastasizing soft tissue tumor of the pelvic soft tissues and perineum. This rare tumor occurs almost exclusively in adult women. We report four cases occurring in adult men, one each located in the scrotum, inguinal region, spermatic cord, and pelvis. The tumors were infiltrative, and were composed of fibromyxoid matrix sparsely populated by bland-looking spindled and stellate cells with delicate cytoplasmic processes. There were haphazardly scattered small and large blood vessels, some of which exhibited hypertrophy or hyalinization of the wall. Immunohistochemically, the stromal cells stained consistently for vimentin and variably for musclespecific actin, but not a-smooth muscle actin, desmin, and S-100 protein. None of the four tumors recurred in follow-up times from 11 months to 6 years, although two previously reported cases in men recurred. This uncommon tumor occurring around the genital region in men merits wider recognition because of its potential for recurrence. It should be distinguished from benign tumors with low risk of recurrence on one hand, and from malignant myxoid tumors with metastatic potential on the other.

Primary vascular tumors of lymph nodes other than Kaposi's sarcoma. Analysis of 39 cases and delineation of two new entities.

Primary vascular tumors of lymph nodes other than Kaposis sarcoma are very rare, as attested to by only a handful of case reports in the literature. Based on an analysis of 39 such cases, we could distinguish five major groups. Hemangiomas of capillary/cavernous, lobular capillary, and cellular types were composed of compact aggregates of blood-filled vessels, variable in size, that replaced the nodal architecture partly or almost completely; some appeared to have originated in the hilum or medulla. These hemangiomas either represented incidental findings in lymph nodes or were seen with solitary lymph node enlargement; the evolution was benign with no recurrence. A distinctive benign lesion occurring exclusively in inguinal lymph nodes, which we propose designating “angiomyomatous hamartoma,” showed replacement of the nodal parenchyma by smooth muscle cells and fibrous tissue, in continuity with exuberant proliferation of muscular vessels in the hilum. Epithelioid vascular tumors, characterized by plump endothelial cells with dense eosinophilic cytoplasm and numerous vacuoles, exhibited a range of differentiation, from hemangioma with well-formed vascular channels (with or without tissue eosinophilia) to hemangioendotheliomas composed predominantly of cords and sheets of tumor cells lying in a hyaline-myxoid matrix. Epithelioid hemangioendothelioma was particularly likely to be mistaken for metastatic carcinoma, and local recurrence could occur. A variant, the spindle and epithelioid hemangioendothelioma, was characterized by the presence of an additional component of spindle cells. Another tumor we found, polymorphous hemangioendothelioma, is a previously uncharacterized borderline malignant vascular tumor exhibiting solid, primitive vascular and angiomatous patterns and relatively bland cytologic features. Lymphangiomas of lymph nodes usually showed simultaneous multifocal and extranodal involvement and were characterized by cystic endothelium-lined spaces filled predominantly with lymph fluid. It is important to recognize these primary vascular tumors of lymph nodes to avoid mistaking them for a variety of benign vasoproliferative lesions, Kaposis sarcoma, angiosarcoma, and metastatic cancer.

Cytogenetic Abnormalities in Natural Killer Cell LymphomaLeukaemia - Is There a Consistent Pattern?

The group of putative natural killer cell lymphomas, also known as NK/T cell lymphomas (nasal and nasal-type) has been characterized only in recent years. Whilst a good amount of clinical information has been gathered on this group of uncommon lymphoid neoplasms, there is little information on the cytogenetic or molecular alterations. A review of the literature shows that chromosomal abnormalities are indeed commonly found in these tumours, and aberrations involving chromosome 6q are most frequent. Other non-random abnormalities include +X, i(1q), i(7q), +8, del(13q), del(17p), i(17q), and 11q23 rearrangement. It appears that deletions of the chromosome 6 at around q21-23 region is the commonest recurrent chromosomal abnormality, and fluorescence in situ hybridisation studies have confirmed the occurrence of deletions at 6q22-23 in the CD3- CD56+ tumour cells. Search for the involved genes located in this chromosome region can potentially shed light on the molecular pathogenesis of the natural killer cell neoplasms.

Molecular Profiling Improves Classification and Prognostication of Nodal Peripheral T-Cell Lymphomas: Results of a Phase III Diagnostic Accuracy Study

PURPOSE The differential diagnosis among the commonest peripheral T-cell lymphomas (PTCLs; ie, PTCL not otherwise specified [NOS], angioimmunoblastic T-cell lymphoma [AITL], and anaplastic large-cell lymphoma [ALCL]) is difficult, with the morphologic and phenotypic features largely overlapping. We performed a phase III diagnostic accuracy study to test the ability of gene expression profiles (GEPs; index test) to identify PTCL subtype. METHODS We studied 244 PTCLs, including 158 PTCLs NOS, 63 AITLs, and 23 ALK-negative ALCLs. The GEP-based classification method was established on a support vector machine algorithm, and the reference standard was an expert pathologic diagnosis according to WHO classification. RESULTS First, we identified molecular signatures (molecular classifier [MC]) discriminating either AITL and ALK-negative ALCL from PTCL NOS in a training set. Of note, the MC was developed in formalin-fixed paraffin-embedded (FFPE) samples and validated in both FFPE and frozen tissues. Second, we found that the overall accuracy of the MC was remarkable: 98% to 77% for AITL and 98% to 93% for ALK-negative ALCL in test and validation sets of patient cases, respectively. Furthermore, we found that the MC significantly improved the prognostic stratification of patients with PTCL. Particularly, it enhanced the distinction of ALK-negative ALCL from PTCL NOS, especially from some CD30+ PTCL NOS with uncertain morphology. Finally, MC discriminated some T-follicular helper (Tfh) PTCL NOS from AITL, providing further evidence that a group of PTCLs NOS shares a Tfh derivation with but is distinct from AITL. CONCLUSION Our findings support the usage of an MC as additional tool in the diagnostic workup of nodal PTCL.