Sessile Serrated Lesion of the Appendix in a Teenage Girl.

According to the literature, serrated lesions and polyps of the appendix are extremely rare in children or teenagers. Herein, we present the pathologic and molecular features of a sessile serrated lesion (SSL) that was incidentally found in the appendix of a teenage girl. Our findings not only illustrate that appendiceal SSL may occur in young patients such as teenagers but also confirm further that BRAF V600E mutation may be found in a subset of these neoplastic lesions.

Lymphoplasmacytic plaque in children: Case report and literature review.

We report a case of benign lymphoplasmacytic plaque (LPP) in a child. These asymptomatic erythematous papulonodular lesions are an emerging clinicopathological entity. Herein, we describe a previously unreported site for LPP lesions, namely, the volar wrist and the distal ipsilateral palm.

Tumor-forming plasmacytoid dendritic cells associated with myeloid neoplasms. Report of a peculiar case with histopathologic features masquerading as lupus erythematosus.

Plasmacytoid dendritic cells (PDC) belong to a subtype of dendritic cells that are normally absent in healthy skin. In some inflammatory diseases of the skin, especially lupus erythematosus (LE), these cells are occasionally recruited in great amounts, which can be used as a helpful clue for diagnosis. Rarely, PDC may also accumulate in the skin of patients with myeloid leukemia, a yet poorly known condition currently called 'tumor-forming PDC associated with myeloid neoplasms'. In this study, we describe a patient with unsuspected chronic myelomonocytic leukemia who developed cutaneous lesions characterized by a dermal infiltrate rich in PDC. Similarly to LE, such neoplastic PDC were accompanied by interface dermatitis-like changes, but displayed an aberrant phenotype and shared the same chromosomal abnormality with the leukemic cells identified in the bone marrow, thus revealing the neoplastic nature of the process. This observation illustrates that tumor-forming PDC associated with myeloid neoplasms may microscopically mimic LE in some patients. Accordingly, a hematologic workup is recommended in any skin lesion featuring excessive numbers of PDC, even if morphological alterations suggestive of interface dermatitis are found.

Fibrin-Associated EBV-Positive Large B-Cell Lymphoma Incidentally Found Within a Multinodular Goiter.

Fibrin-associated diffuse large B-cell lymphoma (fibrin-associated DLBCL) is a very rare subtype of Epstein-Barr virus (EBV)-associated DLBCL that usually develops within fibrin-rich lesions such as cardiac myxoma, chronic hematoma, thrombus, pseudocysts or cysts, prosthetic devices or breast implants. The pathogenesis as well as the clinicopathologic features of this usually indolent lymphoproliferative disorder, which are based on the analysis of a relatively limited number of cases, are still poorly known. Herein, we report a case of fibrin-associated DLBCL that was incidentally found within a multinodular goiter, a location not yet reported to our knowledge. Our findings not only illustrate further the specific nature of this peculiar lymphoproliferative disorder but also allow some interesting comments on its pathogenesis.

Cutaneous accumulation of plasmacytoid dendritic cells associated with acute myeloid leukemia: a rare condition distinct from blastic plasmacytoid dendritic cell neoplasm.

A cutaneous infiltrate composed of plasmacytoid dendritic cells may occasionally occur in a patient suffering from a myeloid neoplasm. To date, the clinical and pathological features associated with this event remains poorly characterized. Herein, we report a patient with acute myeloid leukemia who developed pruritic papules or erythematous plaques scattered on the skin. Microscopic examination showed a dermal infiltrate rich in plasmacytoid dendritic cells expressing CD4, CD43, CD68, granzyme B, CD123, CD303 [blood dendritic cell antigen 2 (BDCA-2)], CD2-associated protein (CD2AP) and T-cell leukemia/lymphoma oncogene 1 (TCL1). Our observation illustrates further that cutaneous lesions associated with some myeloid neoplasms, especially those featuring a monocytic component, may be composed of plasmacytoid dendritic cells. Because of differences in clinical, pathological and genetic features, this rare condition should be distinguished from blastic plasmacytoid dendritic cell neoplasm.

Lymph node involvement by enteropathy-like indolent NK-cell proliferation.

Natural killer (NK)-cell enteropathy (NKCE) and lymphomatoid gastropathy (LG) are closely related lymphoproliferative disorders (LPDs) composed of mature and Epstein-Barr virus (EBV)-negative NK-cells. Although these uncommon and indolent lymphoid proliferations mostly arise within the gastrointestinal (GI) tract as their designations implies, a few cases have been reported outside the GI tract. We hereby describe a unique case of lymph node infiltration by such EBV-negative NK-cell proliferation fortuitously found during routine examination of a gallbladder resected for biliary lithiasis. The histologic, phenotypic, and molecular features of this NK-cell proliferation, which were very similar if not identical to those previously reported in NKCE or LG, suggest that similar indolent EBV-negative NK-cell LPDs may also occasionally involve lymph nodes.

Plasmablastic microlymphoma occurring in human herpesvirus 8 (HHV-8)-positive multicentric Castleman's disease and featuring a follicular growth pattern.

Plasmablastic microlymphoma (PML) is defined as the accumulation of monotypic but polyclonal plasmablasts in lymphoid tissues involved in human herpes virus 8 (HHV-8)-positive multicentric Castleman's disease (MCD). So far, the nature of this very rare condition remains poorly determined. In this study, we describe a human immunodeficiency virus (HIV)-seropositive patient who developed a PML in the setting of HHV-8-positive MCD. In contrast to the cases previously reported, most of the plasmablasts in our patient were localized within the germinal center (GC) of lymphoid follicles. These plasmablasts expressed the multiple myeloma-1/interferon regulatory factor-4 (MUM1/IRF4) protein as well as IgMlambda in a monotypic fashion. They did not show any immunoreactivity with antibodies directed against Pax-5, CD20, CD79a, CD10, CD30, CD23, CD138, epithelial membrane antigen (EMA) or BCL-6. These cells exhibited a high proliferation rate, expressed the HHV-8 latent nuclear antigen-1, and secreted the HHV-8 viral homologue of human interleukin-6. Polymerase chain reaction analysis did not demonstrate any clonal rearrangement of the genes coding for the heavy chain of the immunoglobulin. Moreover, no Epstein-Barr virus (EBV) RNA transcript could be found, using in situ hybridization. The present case illustrates that PML may arise within the GC of lymphoid follicles in the absence of EBV coinfection. In our opinion, PML occurring in MCD likely represents a variant of HHV-8-positive MCD in which lytic HHV-8 replication is particularly prominent, due to a local or systemic immune imbalance.

Clinical added-value of 18FDG PET in neuroendocrine-merkel cell carcinoma.

Merkel cell carcinoma (MCC) is a rare and highly malignant skin cancer with neuroendocrine differentiation. We studied the potential value of 18FDG PET in the management of MCC. Eleven patients with MCC were examined by 18FDG PET and PET-CT for staging purpose (n=4) or for detection of recurrence (n=7). Qualitative and quantitative interpretation of PET studies was performed routinely. 18FDG PET observations were compared to clinical and radiological findings. In 6 patients, PET findings were also compared to histology. In 7 patients, the 18FDG tumor uptake was compared to the MCC proliferative activity expressed by the Ki-67 index. 18FDG PET was contributive in 10/11 MCC patients. In 7 patients, 18FDG PET detected focal lesions or a disseminated stage of the disease including dermal, nodal and visceral metastases. In 3 patients, a normal 18FDG PET confirmed complete remission of disease. Most MCC patients exhibited highly 18FDG-avid sites suggestive of increased glucose metabolism. This imaging pattern was related to a high proliferative activity (Ki-67 index >50%). In 1 patient with a weakly proliferative nodal MCC (Ki-67<10%), a false negative result was yielded by metabolic imaging. In 4/11 patients, 18FDG PET revealed an unsuspected second neoplasm in addition to MCC. It is concluded that whole-body 18FDG PET may be useful in the management of MCC patients. However, a normal 18FDG PET aspect cannot rule out MCC with low proliferative activity.

Clinically unsuspected tonsillar sarcoidosis in a child revealed by routine histologic examination.

In most hospitals, making a microscopic examination to tonsil and adenoid specimens from pediatric patients who present recurrent infections has become a standard practice. However, studies have shown that systematic examination of tonsils and adenoids was not needed for individual aged 21 or less. In this context, we describe the third report of an unsuspected tonsillar sarcoidosis revealed by histologic examination. A 5-year-old white girl was referred to our department because of frequent nasal and pharyngeal infections. Both tonsillectomy and adenoïdectomy were performed. Histologic evaluation revealed noncaseous epithelioid granulomas morphologically compatible with a diagnosis of sarcoidosis. Our observation illustrates the benefit of histological analysis in every tonsillectomy and adenoïdectomy specimen.

Genomic profiling of myeloma: the best approach, a comparison of cytogenetics, FISH and array-CGH of 112 myeloma cases.

BACKGROUND: Chromosome abnormalities are important prognostic factors in myeloma allowing risk stratification of patients. Different techniques are available for their detection including cytogenetics, Fluorescent In Situ Hybridisation (FISH) and array Competitive Genomic Hybridisation (CGH). This study aimed to assess the validity and usefulness of each technique in a diagnostic setting. METHODS: 112 myeloma cases were analysed by whole bone marrow cytogenetics and by FISH and array CGH performed on purified plasma cell populations. RESULTS: Clonal abnormalities were identified in 30% of cases by cytogenetics and 97% by FISH and array CGH. By combining array and FISH results abnormalities were detected in 99% of cases and, if cytogenetic analysis was also considered, abnormalities were detected in 100% of cases. CONCLUSIONS: Cytogenetic analysis is of limited value in myeloma. Array CGH and FISH are highly specific tests allowing the identification of aberrations in virtually all cases. The two techniques are complementary and need to be combined in order to provide a comprehensive analysis of all clinically relevant aberrations in myeloma.

De novo CD5-positive diffuse large B-cell lymphoma of the skin arising in chronic limb lymphedema.

We report the case of a 79-year-old woman with a longstanding lymphedema of the right arm who developed a skin lymphoma involving the right wrist area. Microscopically, the lesion was composed of numerous centroblasts infiltrating both the dermis and the subcutaneous tissue. Phenotypic investigations showed expression of CD20, CD79a, and bcl-2 protein by neoplastic cells. In addition, these cells were CD5 positive. No expression of anaplastic large cell lymphoma kinase (ALK), CD10, CD23, CD30, CD43, bcl-6, cyclin D1, p53 or p16INK4a could be seen. Polymerase chain reaction (PCR) analysis demonstrated a clonal rearrangement of the genes coding for the kappa light chain of the immunoglobulin (Ig). No rearrangement of the genes coding for the Ig heavy chain, t(14;18) or t(11;14) chromosome translocations, or Epstein-Barr virus (EBV) genomic sequences could be found. The tumor was classified as stage IE and was first cured by complete surgical excision. Nineteen months later, a recurrence was noted in the right elbow area. This study further illustrates that lymphoma of the skin may complicate chronic limb lymphedema. Like most of the previously reported cases, this neoplasm belonged to the category of diffuse large B-cell lymphoma. However, it showed CD5 expression as a singular feature.