Evaluation of the Italian cytological subclassification of thyroid indeterminate nodules into TIR-3A and TIR-3B: a retrospective study of 290 cases with histological correlation from a single institution.

PURPOSE: The Italian consensus to classify thyroid cytology has provided a standardized reporting scheme, including the subdivision of indeterminate for malignancy TIR-3 category into TIR-3A (low-risk) and TIR-3B (high-risk). We aimed to present our experience on this subclassification by evaluating risks of malignancy and the validity in sorting nodules with dissimilar risks. Another aim was to compare our performance against the Bethesda system. METHODS: Fine-needle aspirates of 290 TIR-3 that underwent thyroid surgery at our hospital (2008-2013) were reviewed and divided into TIR-3A or TIR-3B, and AUS/FLUS or FN/SFN. Cytological diagnoses were then correlated to histology. Results were evaluated using univariate analysis. RESULTS: The subclassification into TIR-3A and TIR-3B differentiated hyperplastic nodules (p = 0.000) but not adenomas (p = 0.090). Rates of malignancy were significantly different between TIR-3A (10.2%) and TIR-3B (43.8%); TIR-3B malignancies were often papillary carcinomas (83%). TIR-3A/TIR-3B accounted for high sensitivity (84.5%; CI 79.7-88.4%), accuracy (64.1%; CI 58.6-69.6%) and NPV (89.8%; CI 85.6-93.0%) as opposed to modest specificity (55.8%; CI 49.9-61.6%) and PPV (43.8%; CI 38.1-49.8%). The rate of malignancy in AUS-FLUS was higher than in TIR-3A (p = 0.007), whereas it was not different between FN/SFN and TIR-3B (p = 0.337). Sensitivity of the Bethesda system was significantly lower respect to the Italian system. CONCLUSIONS: The study supports the Italian consensus showing a different risk of malignancy for TIR-3A as compared to TIR-3B. TIR-3A/TIR-3B subclassification is valid to sort out benign nodules (high NPV) and malignancies (high sensitivity) but not adenomas (modest specificity, low PPV). In our experience, sensitivity is the main difference between Italian and Bethesda systems.

Diagnostic utility of thyroglobulin measurement in the fine needle aspirates from cervical lymph nodes: a case report.

Fine needle aspiration cytology (FNAC) is the more accurate diagnostic method for cervical lymph node (CLN) metastasis from differentiated thyroid cancers (DTC). However, FNAC diagnosis of cystic CLN is, in most cases, uninformative due to inadequate cellularity. Recently, thyroglobulin (Tg) detection in FNAC needle washout fluid has been shown to improve the diagnostic accuracy of FNAC, and its routine association with cytology is recommended. We here describe the case of a 20 yr old girl complaining of the recent appearance of palpable non-painful laterocervical nodes in the neck. Ultrasound examination revealed the presence of 3 cystic CLNs and 2 mixed thyroid nodules, with the larger one showing irregular margins. On the latter, and on 2 larger CLNs, FNAC was performed, and both Tg protein and mRNA were determined in the needle washout. The cytological analysis was not diagnostic for the two CLNs, while that of the thyroid nodule reported the presence of colloid and groups of thyrocytes with normal morphology. Both CLNs showed, however, high levels of Tg protein and were positive for Tg mRNA, suggestive of metastatic DTC. Based on these findings, the FNAC analysis was performed on the second smaller thyroid nodule suggesting (Tir4) the presence of PTC. The patient was then subjected to total thyroidectomy with lymph nodes resection of the central and homolateral compartments. The histological diagnosis confirmed the presence of a PTC in the small nodule and metastatic lymph nodes. In conclusion, this case confirms that the cytological diagnosis of cystic lymph nodes is challenging, and that the measurement of Tg protein and/or mRNA in the needle washout may overcome this limitation.

Surgical strategies in patients with medullary thyroid carcinoma.

OBJECTIVES: Aim of the study was to identify, in 59 operated patients affected by medullary thyroid carcinoma (MTC), the recurrence rate, survival, mortality and incidences of surgically derived hypoparathyroidism and recurrent laryngeal nerve injury (RLNI). MATERIALS AND METHODS: Based on pre-surgical diagnosis of the 59 patients included in the study, 35 underwent total thyroidectomy with central neck dissection (Group A), 14 total thyroidectomy, central neck dissection and monolateral functional neck dissection (Group B) and 10 total thyroidectomy central neck dissection, bilateral functional neck dissection (Group C). Overall survival, recurrences, incidence of hypoparathyroidism and RLNI were evaluated. RESULTS: The survival and recurrences were not statistically different among the three Groups. In Group B there was major probability of re-operation (p=0.042). The mortality rate was clearly major in Group C (p=0.003) due to the stage of pathology. Group C showed a high number of hypoparatiroidism compared to Group B, and B compared to A. In Group A there was only one unexpected RLNI; in 5 cases, 3 in Group B and 2 in Group C, there were a necessity laringeal section due to nerve tumor involvement. CONCLUSIONS: From our data it appears clearly that disease outcome following the different surgical approaches is mainly determinated by the stage of the disease at diagnosis. However, the finding that patients in Group A and B showed a high rate of local-regional recurrences may suggest that homolateral lymphadenectomy in Group A patients and bilateral lymphadenectomy in Group B patients should be always performed.

Phenotypic changes of the thyrocyte membrane in papillary thyroid carcinoma. A three-dimensional study.

Aim of the study was to assess the presence of structural changes in the complex carbohydrate chains of thyroid epithelia undergoing neoplastic transformation. We investigated thyroid cells from neoplastic lesions using a panel of lectins with specific affinity for distinct carbohydrate residues. Sixty samples of thyroid tissue, including normal, hyperplastic and neoplastic lesions were obtained from surgical specimens and blindly evaluated with lectin stains. Confocal microscopy was used to obtain three-dimensional (3-D) images of the samples with a positive reaction. Wheat germ agglutinin (WGA) was consistently positive on the apical membrane of papillary thyroid carcinomas (PTC), was weakly expressed in follicular carcinomas (FC) and resulted negative in normal thyrocytes and in benign conditions. The 3-D microscopy model showed that the WGA staining pattern in light microscopy corresponds to a continuous layer on the luminal surface of both papillary and tubular structures of PTC cells. The other lectins under evaluation did not provide any significant result. In conclusion, in PTC the apical border of thyrocytes showed a strong, specific and consistent staining with WGA. These findings may be related to a modified interaction of thyroglobulin molecule with thyroid cell membrane and with the expression of molecules that are involved in the process of tumorigenesis and tumor progression.

Microdeletions in 9p21.3 induce false negative results in CDKN2A FISH analysis of Ewing sarcoma.

Deletion of the CDKN2A locus at 9p21.3 has been reported to be a poor prognostic sign in the Ewing sarcoma family of tumours. In clinical applications CDKN2A deletion is primarily detected using fluorescent in situ hybridisation (FISH) with a commercial probe, size approximately 190 kb. Due to limitations in resolution, FISH analysis may fail to detect microdeletions smaller than 190 kb. In the present study, we performed 44K array comparative genomic hybridisation (CGH) on eleven Ewing sarcoma cell lines and 26 tissue samples in order to define the sizes of 9p21.3 deletions. Microarray CGH analysis revealed 9p21.3 deletions encompassing the CDKN2A locus in eight cell lines (73%) and in six tumours (23%). In four cases (two cell lines and two tissue samples) the deletion was less than 190 kb in size. In one cell line sample, we detected a microdeletion of approximately 58 kb in 9p21.3 harbouring the CDKN2A locus. We confirmed this result using 244K microarray CGH and TaqMan quantitative RT-PCR analysis and further performed FISH analysis on this cell line sample. Here, we show that CDKN2A FISH analysis can give false negative results in cases with small microdeletions. Our results suggest that new and more accurate FISH methods should be developed for detection of deletions in the CDKN2A locus.

Actinomycosis of submandibular gland: an unusual presentation.

An unusual presentation of oro-facial actinomycosis, mimicking the clinical appearance of a malignant lesion is reported. The patient, a 74-year-old female, presented with a right submandibular mass, which slowly grew in size over a period of about 2 months, and a modest dysphagia. A painless cervical mass was palpable over the submandibular region. The rhino-pharyngo-laryngeal region, explored by flexible fiberoptic examination, was normal. At ultrasonography, a 2x2 cm infiltrating dyshomogeneous mass, involving the right submandibular gland, was visible. No connection with adjacent organs was found. There was no associated cervical lymphoadenopathy. Ultrasound-guided fine-needle aspiration cytology, performed on lesion, revealed no evidence of malignancy. The presence of characteristic colonies of actinomyces infection was found. The patient was treated initially with tetracycline chloridrate 100 mg: 1 tablet every 12 hours for 7 weeks, but a repeat ultrasonography showed no resolution. A further fine-needle aspiration cytology showed no actinomyces infection in the specimen. The patient was treated with methylprednisolone, 20 mg every 24 hours, for 5 days. After steroid treatment, the patient has been well and, upon repeat ultrasonography, total resolution of the submandibular lesion was confirmed. In conclusion, the clinical presentation of cervicofacial actinomycosis is variable and may mimic a malignant lesion or chronic granulomatous infections. Diagnostic and therapeutic findings are discussed.

Increased thrombin generation and circulating levels of tumour necrosis factor-alpha in patients with chronic Helicobacter pylori-positive gastritis.

BACKGROUND: Conflicting data have been reported concerning the relationship between Helicobacter pylori infection and coronary heart disease. AIM: To evaluate clotting system activation and plasma levels of tumour necrosis factor-alpha, a procoagulant cytokine, in patients with H. pylori-positive and -negative gastritis. METHODS: Three groups of patients were identified: 38 with H. pylori-positive gastritis, 18 with H. pylori-negative gastritis, and 40 H. pylori-negative controls with normal gastric mucosa. Plasma levels of prothrombin fragment 1 + 2 (F1 + 2) and tumour necrosis factor-alpha were assayed. Patients were also controlled after 2 and 6 months following standard H. pylori eradication treatment. RESULTS: At baseline, fragment 1 + 2 and tumour necrosis factor-alpha levels in H. pylori-positive patients were significantly higher than those in H. pylori-negative patients with gastritis (P < 0.05 and P < 0.01, respectively). After H. pylori eradication, fragment 1 + 2 and tumour necrosis factor-alpha levels showed a significant decrease at 2 months (P = 0.03 and P = 0.02, respectively) and a further reduction at 6 months, reaching levels observed in H. pylori-negative patients and controls. CONCLUSIONS: The increase thrombin generation rate and the correlation of plasma fragment 1 + 2 and tumour necrosis factor-alpha levels in H. pylori-positive patients suggest a role for inflammation in mediating the relationship between H. pylori infection and activation of the clotting system.

[Common bile duct stones: the surgical treatment is always valid]. / La calcolosi del coledoco. Il trattamento chirurgico resta sempre valido.

AIM: The treatment of common bile duct stones has changed with the new therapeutic techniques, that have replaced the conventional therapy, represented by surgery. Anyway, they could cause some problems, that must be regarded. Therefore, we wish to confirm the importance of the conventional surgery in the management of patients with common bile duct stones. METHODS: A total of 147 patients were operated for common bile duct stones (73 in emergency and 74 in election). The intraoperative cholangiography was carried out in 141 patients and a choledocoscopy in 130 patients. A drain of Kehr was positioned in 120 patients, a bilio-digestive anastomosis in 26 cases and in 1 case there was a direct suture of the common bile duct without drain. All patients were treated with a short-term antibioticotherapy, protracted to 5 days in the emergency cases. In the patients with the drain of Kehr there was a control cholangiography after 7 days from operation and it was removed after 25 days. The analysis of the results was done dividing the patients according to the age: <75 years old and >75 years old. RESULTS: Nobody died during the operation. Complications were 17.4% in the patients >75 years old and 2,6% in the patients <75 years old. There were 2 death, in the postoperative period, for the group >75 years old. Cases operated in emergency were 68.1% of "old" patients and 37.2% of "young" patients. The postoperative period was 14.9+/-9.2 days for the "old" group and 10.9+/-5.2 days for the "young" group. CONCLUSIONS: The treatment of common bile duct stones is still a surgical treatment, particularly for "old" patients.

A one-generation cluster of malignant mesothelioma within a family reveals exposure to asbestos-contaminated jute bags in Naples, Italy.

Substantial evidence supports the role of asbestos in malignant mesothelioma. Clustering for this malignancy among relatives not only suggests genetic susceptibility as a relevant component but also provides a clue to investigate non-occupational sources of exposure. We identified five cases of malignant mesothelioma within one family with exposure to asbestos experienced during childhood, as 'next door' residents of a workshop recycling asbestos-contaminated jute sacks in Naples, Italy. This cluster discloses the health risk in the reuse of bags that previously had contained asbestos. Furthermore, it emphasizes the role of asbestos in the genetic-environmental interaction issue of malignant mesothelioma.

Localization and expression of thyroid hormone receptors normal and neoplastic human thyroid.

The aim of this study was to investigate the regional expression of thyroid hormone nuclear receptor forms (TR(alpha) and TR(beta)) and isoform (TR(alpha1) and TR(beta2)) mRNAs in normal and neoplastic (benignant and malignant) human thyroid tissue. Tumor specimens from patients with thyroid carcinomas (papillary: 5 cases; follicular: 5 cases; anaplastic: 2 cases), thyroid follicular adenomas (7 cases) and tissue from normal thyroid glands (12 cases) were analyzed by in situ hybridization and semiquantitative RT-PCR for the expression of TR(alpha1) and beta, as well as for the isoform alpha2 that does not bind the hormone. In normal tissues, TR(alpha2) was expressed at lower levels compared to TR(alpha1) (alpha1/alpha2 = 4.3). In papillary and follicular carcinomas, the expression of TR(alpha1) and TR(beta) did not change as compared with normal thyroid tissue and adenomas (0.87 +/- 0.15 SD vs 0.89 +/- 0.17 densitometric units, DU, and 0.15 +/- 0.02 vs 0.14 +/- 0.03 DU, respectively). However, the expression of TR(alpha2) was significantly higher in differentiated carcinomas compared to normal thyroid tissue and adenomas (0.47 +/- 0.05 vs 0.20 +/- 0.05 DU, p < 0.05) with alpha1/alpha2 = 1.4. In anaplastic carcinoma all TRs were absent. We concluded that both normal and pathological thyroid tissues, with the exception of anaplastic carcinoma, express all TRs in thyreocites and that differentiated thyroid carcinomas are associated in enhancing the expression of TR(alpha2) mRNA.

Malignant pleural mesothelioma in bakers and pastry cooks.

BACKGROUND: The occurrence of malignant pleural mesothelioma (MPM) among bakers and pastry cooks has never been documented. CASE REPORTS: We detected eight cases of MPM in bakers, pastry cooks, and biscuit cooks engaged in making, baking/cooking, and selling pastry/bread in two hospital-based series (Rome and Orbassano/Turin, Italy; period 1990-1997; 222 cases). Field-investigations revealed asbestos-containing material (ACM) in ovens for baking bread, that were manufactured prior to the 1980s. CONCLUSIONS: It is suggested that there is a possible new association of the risk of having worked as a baker or pastry cook and MPM. Presumptive source of exposure to asbestos was the use of asbestos-insulated ovens.

DNA copy number changes in familial malignant mesothelioma.

Malignant mesothelioma (MM) is predominantly a sporadic malignancy linked to exposure to asbestos. Clustering of MM in families suggests genetic susceptibility as a contributing factor. We performed comparative genomic hybridization (CGH) analysis on tumor samples from members of a family with MM of the pleura and a history of parental cancer. Our specific aim was to find a recurrent copy number loss indicating the chromosomal area to which a gene underlying the development of MM could be assigned according to the Knudson two-hit hypothesis. We found losses at 1p, 6q, 9p, 13q, and 14q. The copy number changes were very similar to those reported in sporadic cases. Our findings and results from sporadic cases highlight the importance of cloning the genes in the loss sites at 1p, 6q, 14q, and 22q.

The complete mitochondrial DNA sequence of the basal hexapod Tetrodontophora bielanensis: evidence for heteroplasmy and tRNA translocations.

We present the complete 15,455-nt mitochondrial DNA sequence of the springtail Tetrodontophora bielanensis (Arthropoda, Hexapoda, Collembola). The gene content is typical of most metazoans, with 13 protein-coding genes (PCGs), 2 genes encoding for ribosomal RNA subunits, and 22 tRNA genes. The nucleotide sequence shows the well-known A+T bias typical of insect mtDNA; its A+T content is lower (72.7%) than that observed in other insect species, but still higher than that in other arthropodan taxa. The bias appears to be uniform across the whole molecule, unlike other insect taxa, which show increased A+T content in the so-called A+T-rich region. However, the bias is slightly higher in the third codon positions of the PCGs (81.4%). Anomalous initiation codons have been observed in the nad2 and the cox1 genes. In the latter, the ATTTAA hexanucleotide is suggested to be involved in the initiation signaling. All tRNAs could be folded into the typical cloverleaf secondary structure, but the tRNA for cysteine appears to be missing the DHU arm. Long tandemly repeated regions (193 nt) were found in the A+T-rich region, which in turn was shown to have the possibility of forming a complex array of secondary structures. One of these structures encompassed the junction between the repeats. The A+T-rich region was also interesting in that it showed heteroplasmy in the number of repeats. Three haplotypes were found, possessing 2, 3, and 4 identical repeats, respectively. The order of protein coding and rRNA genes in the molecule was determined and was identical to that of all insects studied so far. However, two tRNA translocations were found which were unprecedented among Arthropoda. These involved the trnQ, which was found between the rrnS and the A+T-rich region, and the trnS(ucn), which was located between trnM and trnI. A preliminary phylogenetic analysis based on the amino acid sequence of the PCGs failed to find support for the monophyly of Hexapoda.

Application of an immunodiagnostic method for improving preoperative diagnosis of nodular thyroid lesions.

BACKGROUND: Thyroid cancer is the most common endocrine malignant disease, but preoperative diagnosis remains a challenge. Fine-needle aspiration cytology has greatly improved the clinical management of thyroid nodules, but the preoperative characterisation of follicular lesions is very difficult. Many patients are thus referred to surgery more for diagnosis than for therapeutic necessity. We undertook an international multicentre study to assess the usefulness of immunohistocytochemical staining for two potential markers of malignant thyrocytes. METHODS: Expression of galectin-3 and CD44v6 was tested on 1009 thyroid lesions (tissue specimens and cytological cell-blocks) and 226 fresh cytological samples obtained preoperatively by ultrasound-guided fine-needle aspiration of thyroid nodules (prospective analysis). The test used monoclonal antibodies specific for CD44v6 and galectin-3, the indirect avidin-biotin complex immunoperoxidase method, and 3-amino-9-ethyl-carbazole as substrate. FINDINGS: The sensitivity, specificity, positive predictive value, and diagnostic accuracy of this test method (for coexpression of the two markers) in the prospective analysis were 88%, 98%, 91%, and 97%, respectively. The sensitivity and specificity of galectin-3 immunodetection alone in discriminating benign from malignant thyroid lesions were more than 99% and 98% respectively, and the positive predictive value and diagnostic accuracy were 92% and 99%. INTERPRETATION: The integration of galectin-3 immunostaining with conventional cytomorphological and clinical diagnostic procedures represents a sensitive and reliable diagnostic approach for preoperative identification of thyroid carcinomas. This test method improves the diagnostic accuracy of conventional cytology and provides the molecular basis for a new nosological assignation of the not yet classified thyroid neoplasms of indeterminate malignant behaviour.

Discrepancy between polymerase chain reaction assay and Western blot analysis in the assessment of CagA status in dyspeptic patients.

BACKGROUND: Infection with CagA-positive Helicobacter pylori may be diagnosed by detecting cagA gene by polymerase chain reaction assay (PCR) or serum antibodies against CagA by Western blot analysis. The aim of this study is to evaluate whether results of PCR and Western blot analysis are in agreement in CagA status assessment. PATIENTS AND METHODS: Thirty-six dyspeptic patients with unknown H. pylori status underwent upper gastrointestinal endoscopy to assess the presence of mucosal lesions and to collect six gastric biopsies (three from the antrum and three from the body) for evaluation of H. pylori infection (rapid urease test, histology and PCR for ureA gene) and gastritis. CagA status was assessed by PCR (cagA gene) on two biopsy specimens and by Western blot analysis of serum (CagA-antibodies) in each patient. RESULTS: At endoscopy, nine patients showed normal mucosa, 15 a duodenal ulcer and 12 antral erosions. Twenty-eight patients were found to be H. pylori-positive and eight H. pylori-negative. Of the 28 H. pylori-positive patients, 17 were CagA-positive and five were CagA-negative by both methods, five were CagA-positive by Western blot analysis but not by PCR and one was CagA-positive by PCR but not by Western blot analysis. Of the eight H. pylori-negative patients, none was CagA-positive by PCR, while six were CagA-positive by Western blot analysis. Therefore, the two tests agreed in only 24 patients (67%). In those patients in whom the PCR and Western blot analysis were not in agreement, the histological features appear to suggest that the results of the Western blot analysis should be considered false positives or false negatives. CONCLUSIONS: PCR and Western blot analysis failed to provide comparable data in many cases. Western blot analysis seems to be more likely to give misleading results than PCR. Thus, PCR seems to be the method of choice to assess CagA status.

Estrogen prevents the lipopolysaccharide-induced inflammatory response in microglia.

After neuronal injury and in several neurodegenerative diseases, activated microglia secrete proinflammatory molecules that can contribute to the progressive neural damage. The recent demonstration of a protective role of estrogen in neurodegenerative disorders in humans and experimental animal models led us to investigate whether this hormone regulates the inflammatory response in the CNS. We here show that estrogen exerts an anti-inflammatory activity on primary cultures of rat microglia, as suggested by the blockage of the phenotypic conversion associated with activation and by the prevention of lipopolysaccharide-induced production of inflammatory mediators: inducible form of NO synthase (iNOS), prostaglandin-E(2) (PGE(2)), and metalloproteinase-9 (MMP-9). These effects are dose-dependent, maximal at 1 nm 17beta-estradiol, and can be blocked by the estrogen receptor (ER) antagonist ICI 182,780. The demonstration of ERalpha and ERbeta expression in microglia and macrophages and the observation of estrogen blockade of MMP-9 mRNA accumulation and MMP-9 promoter induction further support the hypothesis of a genomic activity of estrogen via intracellular receptors. This is the first report showing an anti-inflammatory activity of estrogen in microglia. Our study proposes a novel explanation for the protective effects of estrogen in neurodegenerative and inflammatory diseases and provides new molecular and cellular targets for the screening of ER ligands acting in the CNS.

Isolated oropharyngeal Kaposi's sarcoma in non AIDS patient: differences and similarities with spindle-cell haemangioendothelioma.

Vascular tumours rarely affect the oropharynx and overall they can represent a diagnostic challenge since their clinico-histopathological patterns are not always clear. This case report, of an isolated pharyngeal vascular proliferation, allowed the authors to analyse the similarities and differences between Kaposi's sarcoma and spindle-cell haemangioendothelioma. Moreover, it emphasizes the importance of diagnostic tools, such as the human herpesvirus 8 (HHV8) marker, that sometimes may represent the only reliable test for clearly establishing the diagnosis.

Primary effusion lymphoma in HIV-infected patients with multicentric Castleman's disease.

Multicentric Castleman's disease (MCD) and primary effusion lymphoma (PEL) are two B-cell lymphoproliferative diseases associated with Kaposi's sarcoma-associated herpes virus/human herpesvirus-8 (KSHV/HHV-8). Although MCD is considered a prelymphoma state, it is not known whether a pathogenetic link exists between MCD and PEL. This paper reports the clinico-pathological features of four cases of PEL (two pericardial, one pleural, and one peritoneal) developing in the context of HIV-associated MCD. Effusions, lymph nodes, spleen, and additional tissues from three autopsies were examined for morphology/immunophenotype, search for HHV-8 DNA, and assessment of immunoglobulin heavy chain gene (IgH) configuration using polymerase chain reaction (PCR)-based techniques. MCD and PEL samples contained HHV-8 DNA. Clonal IgH rearrangements were detected only in PEL, whereas MCD tissues were polyclonal. Light-chain immunostaining confirmed B-cell clonality in PEL (two lambda, one kappa, one not tested) and polyclonality in MCD. The autopsies revealed different morphological variants of visceral KS and multi-organ atypical infiltrates exhibiting immunoblastic/plasmablastic features reminiscent of PEL morphology, with a restriction of lambda-positive cells. In two cases, using microdissection and IgH PCR analysis, multiple/discrete bands were found in the infiltrates, compatible with polyclonality/oligoclonality. The case showing an oligoclonal IgH ladder contained a rearrangement of identical junctional size to the PEL clone; however, further analysis with PEL-derived clonotypic primers and sequencing of PCR products showed no amplification and nucleotide diversity, respectively, indicating that the two B-cell populations examined were clonally unrelated. These data show that MCD and PEL may co-exist in HIV-infected patients, suggesting a relevant association between these two HHV-8-related disorders. Although a definite clonal relationship between MCD and PEL was not demonstrated, it is hypothesized that in some MCD cases, within expanded polyclonal B-cell populations secondary to HHV-8 infection, clonal expansions may occur that localize into a body cavity, i.e. PEL.