CD45 (leukocyte common antigen) immunoreactivity in metastatic undifferentiated and neuroendocrine carcinoma: a potential diagnostic pitfall

Leukocyte common antigen (CD45/LCA) and keratin expression are generally mutually exclusive in diagnostic surgical pathology. CD45 reactivity is a reliable indicator of the hematolymphoid nature of a tumor, whereas keratin reactivity is typical of epithelial differentiation (carcinomas and some sarcomas). Some lymphomas, however, might lack detectable CD45 expression, whereas occasional ones might express keratins. CD45 immunoreactivity has been considered exquisitely specific for hematopoietic cells. We report three undifferentiated or neuroendocrine carcinomas that showed membrane-associated immunoreactivity for CD45 in addition to showing distinctive keratin cocktail (AE1/AE3) and epithelial membrane antigen reactivity (all cases); also, keratin 7 was demonstrated in one case and keratin 19 in another. Two cases were lymph node metastases of undifferentiated carcinomas, one of them from the lungs and the other of an unknown origin; the former case showed neuroendocrine features. The third case represented a pulmonary large-cell undifferentiated carcinoma. These cases were negative for lineage-specific leukocyte antigens and did not show clonal immunoglobulin heavy-chain gene rearrangements. Electron microscopic studies demonstrated desmosomes and keratin-like tonofilaments in all three cases, thus confirming the epithelial nature of these tumors. The exceptional membrane staining for CD45 seen in these undifferentiated carcinomas might be comparable to experimentally detected incorporation of leukocyte antigens into the cell membranes of nonleukocytic cells in a leukocyte-rich environment. This rare diagnostic pitfall should be considered in the diagnostic surgical pathology of undifferentiated tumors. It is best avoided by employing a panel of leukocyte and epithelial antigens and by use of electron microscopy, if possible.

Differential expression of cyclin D1 in mantle cell lymphoma and other non-Hodgkin's lymphomas

Mantle-cell lymphomas are associated with a characteristic chromosomal translocation, t(11;14)(q13;q32). This translocation involves rearrangement of the bcl-1 proto-oncogene from chromosome 11 to the immunoglobulin heavy chain gene on chromosome 14, resulting in an overexpression of cyclin D1 mRNA (also known as bcl-1 and PRAD1). In the current study performed on paraffin-embedded tissue, cyclin D1 mRNA could be detected in 23 of 24 mantle-cell lymphomas by reverse transcription polymerase chain reaction (RT-PCR) whereas only 9 of 24 demonstrated a t(11;14) by PCR. However, we also found that cyclin D1 mRNA could be detected in the majority (11 of 17, 65%) of non-mantle-cell lymphomas and in a minority of atypical lymphoid hyperplasias (3 of 7, 43%). Cyclin D1 mRNA expression was not observed in floridly reactive lymph nodes (0 of 9) or in unstimulated lymph nodes (0 of 20), suggesting that it is a sensitive adjunct marker for malignant lymphoproliferative processes, but not specific for mantle-cell lymphoma. A semiquantitative RT-PCR assay was developed that compared the ratio of cyclin D1 to the constitutively expressed gene beta2-microglobulin. Using this assay on a limited number of our specimens, cyclin D1 overexpression in mantle-cell lymphoma could be reliably distinguished from its expression in other non-Hodgkin's lymphomas. This assay for cyclin D1 expression, designed for formalin-fixed, paraffin-embedded tissue, was a very sensitive and specific marker for mantle-cell lymphoma.

Expression of CD44 (HCAM) in small lymphocytic and mantle cell lymphoma

Small lymphocytic lymphoma (SLL) and mantle cell lymphoma (MCL) are small B-cell lymphomas that share many morphological and immunophenotypic features, both expressing the T-cell antigen CD5. Because of this, there is speculation that these two lymphomas may have a common origin, both arising from the mantle zone of the lymph node. CD44 (HCAM), a glycoprotein "homing receptor," has been reported as a marker of small B-cell lymphomas for determining behavior as well as the nodal cell of origin. Intensity of CD44 expression also has been correlated with dissemination of lymphoma. We studied 50 cases with classic features of SLL (30 cases) or MCL (20 cases). Immunophenotypic analysis was performed on paraffin sections. All cases of MCL and SLL were CD20 positive; CD5 was expressed in 19 of 25 (76%) SLL and 11 of 15 (73%) MCL. Cyclin D1 was expressed in 11 of 17 (76%) MCL and no cases of SLL. CD43 coexpression was seen in 27 of 29 (93%) SLL and 17 of 19 (89%) MCL. CD23 was positive in 25 of 28 (89%) SLL and 2 of 20 (10%) MCL. Bcl-2 was positive in 18 of 22 (82%) SLL and 15 of 16 (94%) MCL. CD44 was positive with moderate to strong intensity in 11 of 30 SLL and 15 of 20 MCL. Peripheral blood involvement did not correlate with CD44 immunoreactivity. MCL tended to have intense CD44 immunoreactivity, whereas SLL tended to show weaker CD44 intensity. This trend in the intensity of CD44 in MCL suggests that CD44 may be helpful in distinguishing SLL from MCL and possibly elucidating the origin of these CD5-positive B-cell neoplasms.

The blastic variant of mantle cell lymphoma arising in Waldeyer's tonsillar ring

We present three cases of blastic mantle cell lymphoma with an unusual initial manifestation in Waldeyer's ring with methods for differentiating it from other blastic neoplasms of the head and neck. All cases presented with a feeling of fullness in the area of the mass. Morphologically, the tumours were blastic with a high mitotic rate (three to nine per high power field). All were B-cell phenotype with coexpression of CD43. In all cases cyclin D1 and bcl-2 were positive and CD23 negative. Blastic mantle cell lymphoma occurring in Waldeyer's tonsillar ring may be mistaken for other high grade haematopoietic neoplasms. Immunohistochemistry and awareness of this type of lymphoma are helpful in differentiating it from other neoplasms.

Reticulum cell neoplasms of lymph nodes: a clinicopathologic study of 11 cases with recognition of a new subtype derived from fibroblastic reticular cells

Lymph nodes contain nonlymphoid accessory cells including follicular dendritic cells (FDCs), interdigitating dendritic cells (IDCs) and fibroblastic reticular cells (FBRCs). Neoplasms derived from FDCs are uncommon, and those of IDC origin are even more rare. We report the clinicopathologic features of 11 reticulum cell neoplasms, including 2 of FBRC origin. There were seven male patients and four female patients ranging in age from 13 to 73 years. All cases involved lymph nodes (cervical or supraclavicular-6 cases), (abdominal--2 cases), epitrochlear (1 case); two had more than one site of involvement (cervical lymph node and mediastinum--1 case, cervical and abdominal lymph nodes--1 case). One case of FDC tumor had concomitant Castleman's disease, plasma cell variant. Each neoplasm showed similar histology with oval-to-spindle-shaped cells in a storiform or fascicular pattern. Based on immunophenotypic findings, the neoplasms were classified as FDC (five cases), IDC (two cases), FBRC (three cases), and reticulum cell neoplasm, not otherwise specified (one case). The FDC tumors showed immunoreactivity for CD21 or CD35, vimentin, and CD68. The IDC tumors showed strong positivity for S-100 protein and variable positivity for CD68 and CD1a. The cases derived from FBRCs were positive for vimentin, desmin, and smooth-muscle actin. The neoplasm classified as reticulum cell neoplasm, not otherwise specified had similar morphologic features but showed only equivocal positivity for CD68 and vimentin. Follow-up was available for 9 of 11 (82%) cases with a mean of 3.5 years. Four of five patients with FDC tumors were alive with disease when last seen; the fifth is alive and well with no evidence of disease at 4-year follow-up. One patient with IDC tumor had a recurrence in a different nodal site. Two patients with FBRC tumor were disease free at follow-up of 2 years and 8 years, respectively. The patient with reticulum cell neoplasm, not otherwise specified, was alive and disease free 8 years after diagnosis.

Loss of tumor suppressor gene expression in high-grade but not low-grade non-Hodgkin's lymphomas

The products of the MTS1/CDKN2 and retinoblastoma (RB) tumor suppressor genes, p16 and pRB, act as agonists in controlling the late G1 cell cycle checkpoint. Inactivation of either gene occurs in a wide range of human malignant neoplasms. Data on the expression of both genes in the same set of malignant lymphoid neoplasms are scarce. We studied the p16/pRB pathway in low-grade and high-grade non-Hodgkin's lymphomas, using immunohistochemical techniques. Paraffin sections of 9 reactive lymph nodes and 43 low-grade and 60 high-grade malignant lymphomas were reacted with antibodies against pRB and p16. All benign lymph nodes showed a normal pattern of RB and MTS1/CDKN2 expression. Of 101 evaluable lymphomas, only a single high-grade tumor displayed loss of RB reactivity. Loss of p16 was identified in 14 of 55 evaluable high-grade lymphomas but not in any of the low-grade lesions. All but 3 of the RB- and p16-negative cases were diffuse large cell lymphomas, for an abnormality rate of 55% in this category. While loss of RB function was a rare event in human lymphomagenesis, p16 was absent in some 25% of high-grade non-Hodgkin's lymphomas; diffuse large cell lymphomas were the primary target of tumor suppressor gene inactivation.

Bcl-2 immunohistochemistry in a surgical series of non-small cell lung cancer patients

The bcl-2 gene is implicated in oncogenesis by its ability to prolong cell survival through the inhibition of apoptosis, without increasing cell proliferation. An association between immunohistochemical staining for bcl-2 protein and the histological type and prognosis of non-small cell carcinoma was hypothesized by Pezzella et al. (N Engl J Med 329:690-694, 1993). In a case series, we stained formalin-fixed, paraffin-embedded tumor tissue from 106 surgical non-small cell lung cancer patients with an antibody to bcl-2 protein (DAKO clone 124, Carpinteria, CA). The resulting bcl-2 staining data were evaluated for associations with demographic, histological, immunohistochemical, and genetic features, including p53 mutations. Bcl-2 staining was observed in tumors from 29 of 106 (27%) of subjects, but was significantly less frequent in subjects' adenocarcinoma histology (8 of 55, 14.6%) (P = .007). This finding persisted after adjustment for age, gender, stage, grade, smoking history, and disease-free survival. In univariate analyses, no association was seen with age, weight, body mass index, gender, or pack-years smoking; tumor grade, stage, or patient performance status; p53 or c-erbB2 immunohistochemical staining, or p53 mutations. These data agree with earlier reports that bcl-2 staining is less common in adenocarcinomas; however, our data do not support the hypothesis that bcl-2 staining confers a better prognosis overall, in squamous cell carcinoma, or in an older patient population.

Detection of Epstein-Barr virus in transformations of low-grade B-cell lymphomas after fludarabine treatment

Fludarabine is a highly effective chemotherapeutic agent for chronic lymphocytic leukemia/small lymphocytic lymphoma and is also active in other B-cell lymphoproliferative disorders. Although highly efficacious in destroying the malignant B-cells, fludarabine also causes T-cell lymphopenia and immunosuppression. We present five patients given fludarabine for low-grade B-cell lymphoproliferative disorders who showed transformation of the primary neoplasm to a higher grade tumor. Immunohistologic antibody studies were performed on paraffin-embedded tissue sections of the initial tissue (when available) and on the follow-up biopsy specimens for CD20, CD3, CD45RO, CD43, CD30, CD15, and latent membrane protein (LMP-1) for Epstein-Barr virus (EBV). The initial diagnoses in these five patients included chronic lymphocytic leukemia/small lymphocytic lymphoma (three cases), follicle center lymphoma (one case), and Waldenstrom's macroglobulinemia (one case). All of the follow-up biopsy specimens showed scattered Hodgkin's-like cells, and two of the five also showed foci of large-cell transformation. The Hodgkin's-like cells showed CD30 immunoreactivity in four of the five cases and CD15 immunoreactivity in three of the five. Strong immunoreactivity of the large, atypical, Hodgkin's-like cells for LMP-1 of EBV was noted in four cases; in the remaining case, this finding was equivocal. In situ hybridization for EBV-encoded RNA was positive in four of the five cases. Molecular studies by polymerase chain reaction (PCR) showed the presence of EBV in three of the five cases. PCR for detection of immunoglobulin heavy chain demonstrated identical monoclonal rearrangements in the original lymphoma and transformation in one case with available material. The CD4 lymphocyte count in each patient was less than 550/microL, indicating cellular dysfunction. Transformation of low-grade non-Hodgkin's lymphomas after fludarabine therapy might be associated with EBV and severe immunosuppression.

Histologically discordant lymphomas with B-cell and T-cell components

We describe the clinical, histologic, immunophenotypic, and genotypic features of five cases of histologically discordant lymphomas with B-cell and T-cell components. Three patients presented with B-cell lymphoma; T-cell lymphoma subsequently developed. One patient presented with T-cell lymphoma; B-cell lymphoma subsequently developed. One patient presented with synchronous B-cell and T-cell lymphomas. There were three men and two women. The median age at the initial diagnosis of lymphoma was 66 years. The mean interval between the development of the two lymphomas was 83 months. All patients died of disease. The mean survival was 96 months after the initial diagnosis of lymphoma and 14 months after the diagnosis of the histologically discordant lymphoma. Epstein-Barr virus was found in two cases--the B-cell lymphoma in the patient who presented with synchronous lymphomas, and the subsequent T-cell lymphoma in one of the patients who presented with B-cell lymphoma. Based on the results of immunophenotypic and genotypic analyses, these cases likely represent the occurrence of two distinct lymphoid neoplasms rather than histologic progression of the same neoplastic clone. Furthermore, a subset of these cases are Epstein-Barr virus-associated.

Gastric "pseudolymphoma": a retrospective morphologic and immunophenotypic study of 97 cases

BACKGROUND

The term "pseudolymphoma" has been used to describe lymphoid lesions that show: 1) borderline features between hyperplasia and neoplasia or 2) benign tumor-like enlargement of lymphoid tissue. The term pseudolymphoma has been applied to lesions in many anatomic locations, with the stomach being one of the more common sites. In spite of the frequent use of this term, neither the histologic criteria nor the clinical significance of this lesion have ever been clearly defined. Since the description of mucosa-associated lymphoid tissue (MALT) and its corresponding MALT-type lymphomas, the value of the term gastric pseudolymphoma has come into question.

METHODS

The authors reviewed all cases diagnosed as gastric pseudolymphomas at the Armed Forces Institute of Pathology from 1970 to 1985. This period predated the description of low grade B-cell lymphoma of MALT-type. The cases were reclassified in light of current criteria and correlated with immunohistochemical findings and follow-up information. No patients were treated with chemotherapy or radiation therapy.

RESULTS

Seventy-seven of 97 cases formerly diagnosed as pseudolymphoma were determined to be malignant lymphomas; the majority (51 cases) were extranodal marginal zone B-cell lymphomas (MALT-type). The remaining cases included reactive lymphoid hyperplasia associated with chronic follicular gastritis (15 cases) and atypical lymphoid infiltrates (5 cases).

CONCLUSIONS

Most cases previously considered to be gastric pseudolymphomas are, by current criteria, malignant lymphomas. A small proportion are benign reactive lymphoid hyperplasias. Those cases of borderline or inconclusive nature are best diagnosed as atypical lymphoid infiltrates. The term gastric pseudolymphoma should be abandoned.

Gastric "pseudolymphoma": a retrospective morphologic and immunophenotypic study of 97 cases

BACKGROUND

The term "pseudolymphoma" has been used to describe lymphoid lesions that show: 1) borderline features between hyperplasia and neoplasia or 2) benign tumor-like enlargement of lymphoid tissue. The term pseudolymphoma has been applied to lesions in many anatomic locations, with the stomach being one of the more common sites. In spite of the frequent use of this term, neither the histologic criteria nor the clinical significance of this lesion have ever been clearly defined. Since the description of mucosa-associated lymphoid tissue (MALT) and its corresponding MALT-type lymphomas, the value of the term gastric pseudolymphoma has come into question.

METHODS

The authors reviewed all cases diagnosed as gastric pseudolymphomas at the Armed Forces Institute of Pathology from 1970 to 1985. This period predated the description of low grade B-cell lymphoma of MALT-type. The cases were reclassified in light of current criteria and correlated with immunohistochemical findings and follow-up information. No patients were treated with chemotherapy or radiation therapy.

RESULTS

Seventy-seven of 97 cases formerly diagnosed as pseudolymphoma were determined to be malignant lymphomas; the majority (51 cases) were extranodal marginal zone B-cell lymphomas (MALT-type). The remaining cases included reactive lymphoid hyperplasia associated with chronic follicular gastritis (15 cases) and atypical lymphoid infiltrates (5 cases).

CONCLUSIONS

Most cases previously considered to be gastric pseudolymphomas are, by current criteria, malignant lymphomas. A small proportion are benign reactive lymphoid hyperplasias. Those cases of borderline or inconclusive nature are best diagnosed as atypical lymphoid infiltrates. The term gastric pseudolymphoma should be abandoned.

Childhood Hodgkin's disease in the United States: an analysis of histologic subtypes and association with Epstein-Barr virus

Hodgkin's disease (HD) typically has a bimodal age distribution and is less common than non-Hodgkin's lymphoma in the pediatric age group, especially in very young children. Recent reports described a high prevalence of Epstein-Barr virus (EBV) in HD from developing countries in both adult and pediatric populations. In this series, we studied with immunohistochemical analysis 44 cases of pediatric HD from the United States to investigate the association with EBV in developed countries and to determine which subtypes occur in this group. The 44 cases (40 boys, 4 girls; male-to-female ratio, 10:1) were categorized as nodular lymphocyte predominance in 16 (36.4%) of 44; nodular sclerosis in 13 (29.5%); and mixed cellularity in 4 (9.1%). Eleven of the cases were difficult to subclassify by the usual morphologic and immunophenotypic criteria. Of these, eight (18.1%) were designated interfollicular HD, and three were classified as HD "not otherwise specified." EBV LMP was positive in 38.6% of cases: 5 (38.5%) of the 13 with nodular sclerosis; 3 (75%) of the 4 with mixed cellularity; 1 (6.0%) of the 16 with nodular lymphocyte predominance; 7 (87.5%) of the 8 with interfollicular HD; and 1 (33.3%) of the 3 with HD "not otherwise specified." There was a strong association between the age of the patient and EBV expression. In children 4 years or younger, all of the 3 cases were LMP positive; in the 5- to 9-year-old age group, 8 (61.5%) of 13 were LMP positive; and in the 10- to 15-year-old group, only 21.4% were positive. Our results confirm the male predominance in pediatric HD and show an association with EBV, especially in the youngest patients and with the mixed cellularity and interfollicular subtypes. Most, but not all, cases of pediatric HD can be subclassified by traditional criteria.

Inflammatory pseudotumor of lymph nodes: a study of 25 cases with emphasis on morphological heterogeneity

The clinicopathological and immunohistochemical findings in 25 cases of inflammatory pseudotumor of lymph nodes (IPT) are presented. The patients were 13 women and 12 men between 8 and 81 years of age. Clinically, symptoms of prior infection, fatigue, abdominal pain, weight loss, fever of unknown origin, pelvic inflammatory disease, or nausea and night sweats were obtained in 15 patients, whereas six patients presented with asymptomatic lymphadenopathy. In four additional patients, no clinical information was obtained. The involved nodes included cervical, supraclavicular, inguinal, mesenteric, and mediastinal lymph nodes. In two cases, there was synchronous involvement of separate lymph node groups (inguinal and cervical in one case and cervical and mediastinal in another case), whereas in a third patient there was synchronous involvement of the spleen and a paraaortic lymph node. Histologically, the lesions were characterized by a fibrosing/inflammatory process that showed marked heterogeneity and striking variation from case to case. Based on their histological features, the lesions could be classified into three different groups: Stage I was characterized by the appearance of single or multiple small foci containing a spindle cell proliferation admixed with a prominent inflammatory background, with complete preservation of the remainder of the nodal architecture; stage II was characterized by more diffuse involvement of the lymph node with a marked inflammatory response admixed with a prominent myofibroblastic proliferation leading to subtotal effacement of the nodal architecture, often with extension of the process beyond the capsule into perinodal fat; and stage III was characterized by almost complete replacement of the lymph node by diffuse sclerosis with scant residual inflammatory elements and total loss of the normal nodal architecture. Immunohistochemical studies in 20 cases showed a striking number of vimentin- and actin-positive myofibroblastic cells with moderate increase in CD20/CD45+ small lymphocytes and polyclonal plasma cells in the stage I lesions, the emergence of numerous CD68+ histiocytes admixed with lymphocytes, plasma cells, and abundant fibromyofibroblastic cells in the stage II lesions, and only few remaining scattered CD68+ histiocytes and fibroblasts in the stage III lesions. Our findings suggest that inflammatory pseudotumor of lymph node represents an evolving, dynamic process that may adopt different morphological appearances depending on its stage of evolution. Recognition of the various stages of this process may be of importance for differential diagnosis with other fibrosing/inflammatory conditions of lymph nodes.

Primary leiomyosarcomas of the lung: a clinicopathologic and immunohistochemical study of 18 cases

We studied 18 patients with primary malignant smooth muscle tumors of the lung (7 women and 11 men, 5-76 yr old, with a mean age of 50 yr). Lesions varied from 1.7 to 10 cm in greatest diameter. The tumors were classified as low (4 cases), intermediate (2), or high grade (12). Low-grade lesions were characterized by an orderly proliferation of fascicles of spindle cells that intersected at right angles and showed oval-to-spindle cells with cigar-shaped nuclei, minimal pleomorphism, and low mitotic activity, without hemorrhage or necrosis. Intermediate-grade lesions retained the fascicular configuration but showed increased cellularity with atypia and dense chromatin pattern, occasional pleomorphism, and mild increase in mitotic activity. High-grade lesions showed high cellularity, marked pleomorphism and atypia, frequent areas of hemorrhage and necrosis, and high mitotic activity. Immunohistochemical studies in 16 cases showed positive staining of tumor cells with smooth muscle actin in 12, desmin in 5, and coexpression of actin and/or desmin and keratin in 3. Six patients with low- and intermediate-grade lesions were alive and well from 2 to 12 years after diagnosis (mean follow-up time, 6 yr); 8 with high-grade lesions died of their tumors with widespread metastases from 1 to 24 months after diagnosis (median survival time, 5 mo). One patient whose tumor showed features of high-grade leiomyosarcoma was alive and well 12 years after surgery. Three patients with high-grade tumors were lost to follow-up. Our findings suggest that histologic grade may be the most reliable prognostic parameter for predicting clinical behavior in primary leiomyosarcoma of the lung and that smooth muscle actin is the most sensitive immunohistochemical marker for establishing the diagnosis in these tumors. Primary leiomyosarcoma should be considered in the differential diagnosis of pulmonary spindle cell neoplasms; histologic grading may be of value in the planning of therapy and assessment of prognosis for these lesions.

Hodgkin's disease and an extranodal marginal zone B-cell lymphoma in the small intestine: an unusual composite lymphoma

We describe a 74-year-old man who presented with multifocal small bowel lesions, a large mesenteric mass, and enlarged mesenteric lymph nodes. In each of the extranodal sites and in two of three regional lymph nodes, there were classic histologic features of marginal zone B-cell lymphoma with adjacent areas of Hodgkin's disease, mixed cellularity subtype. Immunophenotypic analysis in the areas of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue showed immunoreactivity for CD45RB and CD20 in the malignant small cell population. Conversely, the areas of Hodgkin's disease demonstrated positive immunoreactivity for CD15 and CD30 in the Reed-Sternberg cells and variants. Latent membrane protein for Epstein-Barr virus was also positive in the Reed-Sternberg cells and variants.

Olfactory neuroblastoma and other round cell lesions of the sinonasal region

Sixty-nine round cell lesions of the sinonasal region (22 olfactory neuroblastomas [ONBs], 17 malignant lymphomas, nine Ewing's sarcomas [ES], nine rhabdomyosarcomas, three sinonasal undifferentiated carcinomas, five malignant melanomas, and four pituitary adenomas) were studied in an attempt to define the differential diagnostic capabilities of antibody to MIC2 and bcl-2 in paraffin-embedded tissue in the distinction of these lesions. In addition, antibody to p53 was applied in each case to define the incidence of p53 positivity among these various tumor types. Each of the ES cases was MIC2 positive; each of the other cases was MIC2 negative. Positivity for bcl-2 was confined to two cases, one of them a malignant lymphoma (85% of cells positive) and one an ONB (5% of cells positive). Small numbers of scattered p53-positive cells appeared in the majority of cases studied, without regard for the specific tumor type; only a single case, a malignant lymphoma, showed a majority (approximately 90%) of p53-positive cells. These results indicate that the MIC2 antibody is a useful method by which to distinguish ES from a variety of other round cell lesions that may be encountered in the sinonasal region. The practical applications of antibody to bcl-2 and p53 seem to be much more limited; by contrast, neither bcl-2 positive cells nor abundant p53 cells identified by immunohistochemical analysis seemed to be frequent findings in any of the tumor types studied. Although ONBs have been included with the peripheral primitive neuroectodermal tumors for classification purposes, these tumors diverge from the ES/primitive neuroectodermal tumor family in that they do not seem to share either the MIC2 positivity or the t(11;22) chromosomal translocation that typify the ES/primitive neuroectodermal tumor family of lesions. Although bcl-2 positivity has been associated with a light microscopic finding of an unfavorable histologic pattern in retroperitoneal neuroblastomas, it does not seem that bcl-2 positivity in ONB will select for a clinically distinctive subset of patients.

Lymphoid changes of the nasopharyngeal and palatine tonsils that are indicative of human immunodeficiency virus infection. A clinicopathologic study of 12 cases

We report 12 cases in which the histomorphologic changes of the nasopharyngeal tonsils (adenoids) or palatine tonsils suggest infection with the human immunodeficiency virus (HIV). The patients included 10 men and two women, aged 20 to 42 years (median, 33 years). The clinical presentation included airway obstruction, pharyngitis, fever, and a tonsillar or adenoidal mass lesion. Histologic evaluation of the excised adenoids or tonsils in 10 of the cases demonstrated a spectrum of changes including florid follicular hyperplasia, follicle lysis, attenuated mantle zone, and the presence of multinucleated giant cells (MGC). The latter characteristically localized adjacent to the surface or tonsillar crypt epithelium. Two of the 12 cases showed marked lymphoid depletion with absent germinal centers, plasmacytosis, and stromal vascular proliferation. Immunohistochemical evaluation for HIV p24 core protein showed reactivity in 10 of 12 cases localized to follicular dendritic cell network (FDC), the MGC, scattered interfollicular lymphoid cells, and cells identified within the surface or crypt epithelium. Localization of viral RNA by in situ hybridization paralleled the HIV p24 immunohistochemical findings. Additional significant findings included the presence of both CD-68 and S-100 protein in the MGC and the presence of S-100 protein in dendritic cells. Other than HIV, no microorganisms were identified. At the time of presentation, eight patients were not known to be a risk for HIV infection, nor were they known to be HIV infected or suffering from AIDS. In these patients, HIV infection was suspected on the basis of the histologic changes seen in the resected tonsillar and adenoidal tissue. Serologic evaluation (by enzyme-linked immunosorbent assay), confirmed the presence of HIV infection. Our findings suggest the possibility of HIV dissemination through the upper aero-digestive tract mucosa via target cells, such as intraepithelial dendritic cells, submucosal macrophages, and T-lymphocytes. Subsequent presentation of viral antigens to the tonsillar and adenoidal lymphoid tissues results in enlargement of these structures that clinically may simulate a neoplastic proliferation but causes histomorphologic changes that are highly suspicious for HIV infection even in asymptomatic HIV-positive patients.

Replication of HIV-1 in dendritic cell-derived syncytia at the mucosal surface of the adenoid

Human immunodeficiency virus-type 1 (HIV-1) replicates actively in infected individuals, yet cells with intracellular depots of viral protein are observed only infrequently. Many cells expressing the HIV-1 Gag protein were detected at the surface of the nasopharyngeal tonsil or adenoid. This infected mucosal surface contained T cells and dendritic cells, two cell types that together support HIV-1 replication in culture. The infected cells were multinucleated syncytia and expressed the S100 and p55 dendritic cell markers. Eleven of the 13 specimens analyzed were from donors who did not have symptoms of acquired immunodeficiency syndrome (AIDS). The interaction of dendritic cells and T cells in mucosa may support HIV-1 replication, even in subclinical stages of infection.

Primary diffuse large B-cell lymphoma of the breast. A clinicopathologic study of 31 cases

Primary non-Hodgkin's lymphoma of the breast is a rare neoplasm for which survival data vary among the reported studies. Thirty-one cases of diffuse large B-cell lymphoma of the breast, which had been seen in consultation from 1973 to 1985 at our institution, were reviewed. This represents the largest number of lymphomas of this histologic subtype reported to date in the English literature. Histologic examination and immunophenotypic analysis were performed and the results were correlated with clinicopathologic data. The patient population consisted of 29 females and 2 males with a mean patient age of 58.2 years. At the time of diagnosis, 26 patients had unilateral involvement (16 left, 10 right), and 5 had bilateral disease. Mean tumor size was 3.8 cm. Histologically, all cases showed a diffuse large B-cell lymphoma as classified by the Revised European-American Classification of Lymphoid Neoplasms (R.E.A.L Classification). Immunophenotypic studies on paraffin sections confirmed a B-cell lineage in every case. The majority of patients received chemotherapy and/or radiation therapy. The median survival was 36 months, confirming that this neoplasm has a poor prognosis.

Lipid cell (steroid cell) tumor of the ovary: immunophenotype with analysis of potential pitfall due to endogenous biotin-like activity

Twenty-eight lipid cell (steroid cell) tumors of the ovary were studied by immunohistochemistry using an avidin-biotin complex detection system; 75% of tumors were vimentin positive, 46% were positive for cytokeratin (CAM5.2 antibody), 37% were positive with the cytokeratin cocktail AE1/AE3 and CK1, and 29% were positive for smooth muscle alpha-actin. Three tumors were positive for CD68 (KP-1), a histiocyte marker, and each of the following markers was positive in two cases: desmin, epithelial membrane antigen, neuron-specific enolase, and S-100 protein. All tumors tested were negative for chromogranin A, CD15 (Leu-M1), myoglobin, neurofilament protein, alpha-fetoprotein, carcinoembryonic antigen, and melanoma-associated antigen (HMB-45 antibody). Immunoreactivity for cytokeratins was usually focal, paranuclear, and globoid, while reactivity for actin and vimentin was diffuse and cytoplasmic. Based on these findings, melanomas and some carcinomas should be distinguishable from lipid cell tumors. However, the immunohistochemical profiles of smooth-muscle tumors, other gonadal stromal tumors (granulosa cell tumors, thecomas), and hepatocellular, renal cell, and adrenocortical carcinomas overlap with that of lipid cell tumors, and therefore these tumors may not be distinguishable from lipid cell tumors using this technique. In 10 cases (36%), negative controls exhibited weak to moderate nonspecific cytoplasmic staining. Evidence obtained using a biotin blocking kit, and a monoclonal antibody against biotin, suggests endogenous biotin-like reactivity as the source of the nonspecific staining.

Non-Hodgkin's lymphoma of the sinonasal tract. A clinicopathologic and immunophenotypic study of 120 cases

BACKGROUND

Non-Hodgkin's lymphomas (NHLs) of the sinonasal tract are uncommon neoplasms that can be morphologically difficult to distinguish from destructive nonneoplastic processes or other malignant neoplasms in this site.

METHODS

From the files of the Otolaryngic Tumor Registry-Armed Forces Institute of Pathology from 1965 to 1992, 120 cases of NHL involving the sinonasal tract were selected for which clinical records and paraffin-embedded tissue blocks were available. The histologic features and immunophenotypic findings of each patient were examined, and follow-up data were obtained for 66 (55%).

RESULTS

The ratio of males to females was 1.35:1, and the ages ranged from 3 to 94 years (median, 59 years). Sixty percent of the cases of NHL occurred in the patients' sixth to eighth decades of life. Clinical presentations varied according to histologic type. The low grade lymphomas presented with a nasal cavity or paranasal sinus mass associated with obstructive symptoms. The high grade lymphomas were more likely to present with aggressive signs and symptoms including nonhealing ulcer, cranial nerve manifestations, facial swelling, epistaxis, or pain. Of note, the high grade B-cell lymphomas tended to present with soft tissue or osseous destruction, particularly of the orbit with associated proptosis, whereas the T-cell lymphomas were associated with nasal septal perforation and/or destruction. Sites of disease included the nasal cavity, one or more paranasal sinuses, or multiple regions within the sinonasal tract. Of patients who received adequate follow-up, nodal and extranodal dissemination were identified in a limited number (n = 11). Nodal dissemination occurred in cervical and axillary lymph nodes. Extranodal sites of involvement included the larynx, skin, liver, uvula, kidney, breast, lacrimal gland, testis, and prostate gland. There was a wide spectrum of morphologic types of lymphoma, classified according to the Working Formulation. Immunophenotypic analysis on paraffin embedded tissue sections of all patients demonstrated a B-cell to T-cell ratio of 1.18:1. Treatment primarily included radiotherapy and chemotherapy. Follow-up information was available for 66 (55%) patients ranging from 1 to 16 years (median, 3 years). Of these 66 patients, 24 (36.4%) died of disease, 17 (25.7%) are alive without disease, 13 (19.7%) are alive with disease, and 12 (18.2%) are dead of unrelated or unknown causes.

CONCLUSIONS

Non-Hodgkin's lymphomas of the sinonasal tract are heterogeneous diseases that can be clinically aggressive. The frequency of these lymphomas in the United States cannot be estimated accurately because all of our cases were of histologic slides submitted for consultations. There appears, however, to be a slight B-cell predominance in this population that previously has been observed, unlike in South America and Asia where the majority of cases have a T-cell phenotype.

MIC2 detection in tumors of bone and adjacent soft tissues

The diagnosis of Ewing's sarcoma has been based classically in large part on the exclusion of other similar small round-cell tumors by light microscopic and histochemical criteria. This study was undertaken to explore the use of a recently developed immunohistochemical stain directed against the glycoprotein p30/32MIC2 antigen (the gene product of MIC2), as a diagnostic tool and as a probe for the examination of potential interrelationships among the putative members of the family of peripheral primitive neuroectodermal tumors. Fifty-six small round-cell tumors of bone were selected for study from the files of the Armed Forces Institute of Pathology and Rhode Island Hospital; all tissues had been formalin fixed and paraffin embedded. Nine of 10 Ewing's sarcomas were MIC2 positive, as were 2 of 3 atypical Ewing's sarcomas (small round-cell tumors that diverged from the classic pattern of Ewing's sarcoma by exhibiting a greater degree of cytologic atypia and pleomorphism), and 7 of 8 Askin tumors of the thoracopulmonary region. Ten of 11 mesenchymal chondrosarcomas, 1 primitive neuroectodermal tumor of bone, 10 small cell osteosarcomas, 10 malignant lymphomas, and 3 sarcomas of bone (not additionally subclassified) were negative. The finding of MIC2 positivity in the majority of Ewing's sarcomas and Askin tumors provides additional support for earlier proposals (based on a shared cytogenetic abnormality, among other criteria) that these lesions be considered members of the same family, the peripheral primitive neuroectodermal tumors. The present study, drawing on archival and current case material (including decalcified and undecalcified specimens), indicates that neither the specimen age nor the application of any of a variety of decalcification solutions appears to adversely influence MIC2 staining of paraffin-embedded tissues. This suggests that this antibody has use in retrospective and prospective studies. The rare occurrence of false negative (in the case of Ewing's sarcoma) and positive results in tumors other than peripheral primitive neuroectodermal tumors (as in 1 of the mesenchymal chondrosarcomas) suggests that MIC2 staining should not be relied on as the sole criterion for identification or exclusion of Ewing's sarcomas and related tumors.

The spectrum of immunohistochemical staining of small-cell lung carcinoma in specimens from transbronchial and open-lung biopsies

Immunohistochemistry is increasingly used as an aid in the diagnosis of small-cell lung carcinoma (SCLC). Previous studies have investigated immunohistochemical staining of SCLC with small numbers of antibodies, but few have examined large series with a broad panel of antibodies. For this reason, the authors examined the distribution and intensity of staining of 20 open-lung biopsy (OLB) and 21 transbronchial biopsy (TBB) specimens of SCLC with a panel of epithelial, neuroendocrine, and hormonal markers. Small-cell lung carcinoma stained most frequently with epithelial markers, followed by neuroendocrine and hormonal markers. Similar percentages of OLB and TBB specimens stained for keratin (100% each) and epithelial membrane antigen (100% and 95%, respectively). Unexpectedly, BER-EP4 stained 100% of OLB specimens. Chromogranin A was the most frequent neuroendocrine marker in OLB and TBB specimens (60% and 47%, respectively) followed by neuron-specific enolase (60% and 33%), Leu-7 (40% and 24%), and synaptophysin (5% and 19%). No neuroendocrine immunohistochemical reactivity was found in 24% of TBB specimens and 20% of OLB specimens. Bombesin was the most sensitive hormonal marker (45% of OLB specimens). These results show that keratin, epithelial membrane antigen, and BER-EP4 are reliable epithelial markers for SCLC in both TBB and OLB specimens. In addition, negative staining for neuroendocrine markers, because it can occur in as many as 25% of cases, should not deter the diagnosis of SCLC.

Epithelioid angiosarcoma of the adrenal glands. A clinicopathologic study of nine cases with a discussion of the implications of finding "epithelial-specific" markers

Adrenal epithelioid angiosarcomas (AEA) are rare neoplasms. We report the clinicopathologic features of nine cases of AEA. AEA occurred most frequently in the sixth and seventh decades of life (age range, 45-85 years; median, 60); five cases occurred in men and four in women. Presenting symptoms included abdominal mass with or without pain, weight loss, fever, and weakness. Two cases were asymptomatic; one was discovered during evaluation for other disease(s) and the other at autopsy. All neoplasms were nonfunctioning. Radiographic evaluation demonstrated suprarenal or retroperitoneal neoplasms ranging in size from 6 to 10 cm in greatest dimension. Histologically, the neoplasms were invasive, predominantly arranged in solid sheets or nests, and composed of epithelioid cells. Endothelial cell differentiation was suggested by the transition areas between dilated anastomotic vascular spaces and the sheet-like growth, the cytomorphologic similarity between the endothelial cells lining the discernible vascular spaces and those seen in the solid foci, and the presence of intracytoplasmic vacuolization occasionally containing red blood cells. Endothelial derivation was confirmed by immunohistochemistry including Factor VIII-related antigen (FVIII), CD-34 (hematopoetic progenitor cell antigen), and/or Ulex europaeus agglutinin-1 lectin immunoreactivity (UEA-1) and by ultrastructural findings, including rod-shaped microtubulated bodies and intracytoplasmic lumen formation. In addition, cytokeratin reactivity was seen in seven cases, and B72.3 (tumor-associated glycoprotein-72) reactivity was seen in six. Surgical resection was the treatment of choice, occasionally supplemented by chemotherapy. Three patients are presently alive, free of disease, at 13, 11, and 6 years following diagnosis. Three died with metastatic AEA of the lung, and three died of unrelated causes.

Extranodal sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) of the head and neck

We report 14 cases of extranodal sinus histiocytosis with massive lymphadenopathy involving a variety of head and neck sites. The patients ranged in age from 3 to 70 years (median, 43 years). Nine cases occurred in women and five occurred in men. The clinical presentation varied depending on the site of occurrence and included nasal obstruction, stridor, proptosis, ptosis, decreased visual acuity, facial pain or tenderness, cranial nerve deficits, mandibular tenderness, and mass lesions. Head and neck sites involved by disease included the nasal cavity, paranasal sinuses, nasopharynx, parotid gland, submandibular gland, larynx, temporal bone, infratemporal fossa, pterygoid fossa, meninges, and orbital region. The majority of patients presented with involvement of more than one site. Nodal involvement was identified in four patients. Special stains for microorganisms were negative. The sinus histiocytosis with massive lymphadenopathy cells demonstrated an immunophenotypic profile supporting derivation from macrophage/histiocytic lineage. Treatment varied and included surgical excision with or without adjuvant therapy (chemotherapy, radiotherapy) or steroids. Several patients required more extensive surgery as a result of extension of their disease to adjacent structures or due to recurrent disease. Twelve patients are alive and either free of disease or have persistent disease. Two patients died, one as a result of complications of disease.