Parenteral iron therapy is associated with a characteristic pattern of iron staining on bone marrow aspirate smears.

We developed anecdotal evidence that parenteral iron therapy is associated with a characteristic pattern of iron staining in bone marrow aspirate smears. In this pattern, uniform blue granules are observed within reticuloendothelial cells/stromal cells with Prussian blue staining, many times in curvilinear arrays. To test this hypothesis, marrow cases submitted for morphologic evaluation to our laboratory during an approximate 2-month period in 2006 were assessed for this pattern, and, when it was observed, clinical information was sought to determine if the patient had received parenteral iron. Fourteen cases were identified that displayed the pattern of interest. In 10 of these cases, the pattern was widespread (numerous granules present within virtually all marrow spicules), whereas in 4 cases, the pattern was seen only focally. In all cases in which the pattern was widespread, patients were found to have received parenteral iron at some point before the aspiration procedure. Our findings indicate that parenteral iron therapy is associated with a characteristic pattern of iron staining in bone marrow aspirate smears.

Nodular lymphocyte predominant Hodgkin lymphoma. An immunophenotypic reappraisal based on a single-institution experience.

In our experience, certain commonly cited immunophenotypic features of nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) are not encountered in day-to-day practice. We reviewed 60 cases of NLPHL (18 women, 42 men; median age, 34 years) to discern immunophenotypic features from a large, single-institution cohort. All cases contained lymphocytic and histiocytic (L&H) cells. These cells expressed CD20 in 98% (59/60), CD79a (usually faint) in 87% (27/31), CD30 in 7% (4/59), epithelial membrane antigen in 21% (12/56), bcl-2 in 5% (2/41), and bcl-6 in 83% (30/36) of cases. CD10 was negative in all 36 cases studied; 100% of cases (55/55) demonstrated CD3+ rosettes. Although CD57+ T cells were common within the background infiltrate, CD57+ rosettes were seen in only 48% of cases (15/31) and were rare when encountered. Based on these patterns, we conclude that bcl-2 and bcl-6 may be useful additions to the immunophenotypic analysis of NLPHL, but that the diagnostic usefulness of epithelial membrane antigen and CD57 rosettes may have been overemphasized in previous reports.

Expression of c-FLIP in classic and nodular lymphocyte-predominant Hodgkin lymphoma.

Different molecular pathways are believed to be involved in the pathogenesis of classic Hodgkin lymphoma as opposed to non-Hodgkin lymphoma. Antiapoptotic mechanisms have been proposed for classic Hodgkin lymphoma, including expression of the cellular Fas-associated death domain-like interleukin-1beta-converting enzyme inhibitory protein (c-FLIP), which plays a critical role in resistance to CD95/Fas-mediated apoptosis. In this study, we compare the expression of c-FLIP in the neoplastic cells of classic Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma cases. Sixteen cases of classic Hodgkin lymphoma and 19 cases of nodular lymphocyte-predominant Hodgkin lymphoma were reviewed. Of 16 classic Hodgkin lymphoma cases, 13 cases (81%) were c-FLIP-positive, compared with 6 of 19 (32%) nodular lymphocyte-predominant Hodgkin lymphoma cases. Strong cytoplasmic staining was seen in 7 of 13 c-FLIP-positive classic Hodgkin lymphoma cases, in contrast with only 2 of 6 c-FLIP-positive nodular lymphocyte-predominant Hodgkin lymphoma cases. The 2 cases of nodular lymphocyte-predominant Hodgkin lymphoma with strong c-FLIP expression were associated with transformation to large B-cell lymphoma. An additional 15 cases of diffuse large B-cell lymphoma were studied for c-FLIP expression. All but 1 were c-FLIP-positive. In conclusion, we detected c-FLIP in a significantly lower proportion of nodular lymphocyte-predominant Hodgkin lymphoma cases compared with classic Hodgkin lymphoma cases. Therefore, c-FLIP expression may not be the major mechanism of pathogenesis in nodular lymphocyte-predominant Hodgkin lymphoma. However, strong c-FLIP expression in nodular lymphocyte-predominant Hodgkin lymphoma was associated with transformation to large B-cell lymphoma in 2 cases. c-FLIP expression is not limited to Hodgkin lymphoma, because the majority of diffuse large B-cell lymphoma cases tested were strongly c-FLIP-positive.

CD117 (KIT receptor) expression in Merkel cell carcinoma.

The KIT receptor tyrosine kinase (CD117 antigen) is found in a variety of normal tissue cell types and in several malignant tumors, including acute myeloid leukemia. We recently encountered two tumors initially suspected as acute myeloid leukemia cutis and expressing CD117 that showed punctate positivity for cytokeratin 20 diagnostic for Merkel cell carcinoma. We evaluated 20 additional cases of MCC and found that 21 of 22 tumors (95%) expressed CD117. Intensity of CD117 expression did not appear to correlate with aggressive behavior. While the function of the KIT receptor in MCC is not known, its pathogenic role in other malignant neoplasms suggests the possibility of a similar role in MCC.

Peripheral T-cell lymphoma mimicking marginal zone B-cell lymphoma.

Peripheral T-cell lymphoma (PTCL) may assume a variety of histologic and cytologic appearances. We describe eight cases of PTCL morphologically simulating marginal zone B-cell lymphoma. We reviewed PTCL cases diagnosed in our institution between 1990 and 2000 and selected eight cases for study based on the following criteria: small-cell morphology with abundant, clear cytoplasm and either marginal zone involvement by the neoplastic infiltrate in lymph node biopsies or lymphoepithelial lesions in extranodal biopsies. Histologic features and ancillary studies were reviewed. Patients included six women and two men with a median age of 53 years (range, 35 to 74 years). Six patients were diagnosed with primary nodal PTCL, and two presented with primary extranodal disease. The original diagnosis was PTCL in only four cases; three cases were diagnosed as atypical lymphoid infiltrate, and one case as benign lymphoepithelial lesion. Lymph node biopsies revealed partial effacement of the architecture with residual follicles surrounded by the neoplastic small cells. Extranodal sites included hard palate, tongue, tonsil, and submandibular glands; all but one case demonstrated lymphoepithelial lesions. Monoclonality was demonstrated in six of eight cases (rearrangement of T-cell receptor gene), and three of eight had an aberrant T-cell population by flow cytometry. The differential diagnosis of atypical lymphoid infiltrates with morphologic features of marginal zone B-cell lymphoma should include PTCL. This uncommon morphological mimicry should be recognized, because PTCL is an aggressive disease regardless of morphology and should be treated accordingly.