Comprehensive Investigation of Angiogenesis, PASS Score and Immunohistochemical Factors in Risk Assessment of Malignancy for Paraganglioma and Pheochromocytoma.

A challenging task in routine practice is finding the distinction between benign and malignant paragangliomas and pheochromocytomas. The aim of this study is to conduct a comparative analysis of angiogenesis by assessing intratumoral microvascular density (MVD) with immunohistochemical (IHC) markers (CD31, CD34, CD105, ERG), and S100 immunoreactivity, Ki67 proliferative index, succinate dehydrogenase B (SDHB) expressiveness, tumor size with one the most utilized score Pheochromocytoma of Adrenal Gland Scales Score (PASS), using tissue microarray (TMA) with 115 tumor samples, 61 benign (PASS < 4) and 54 potentially malignant (PASS ≥ 4). We found no notable difference between intratumoral MVD and potentially malignant behavior. The group of potentially malignant tumors is significantly larger in size, has lower intratumoral MVD, and a decreased number of S100 labeled sustentacular cells. Both groups have low proliferative activity (mean Ki67 is 1.02 and 1.22, respectively). Most tumors maintain SDHB expression, only 6 cases (5.2%) showed a loss of expression (4 of them in PASS < 4 group and 2 in PASS ≥ 4). PASS score is easily available for assessment and complemented with markers of biological behavior to complete the risk stratification algorithm. Size is directly related to PASS score and malignancy. Intratumoral MVD is extensively developed but it is not crucial in evaluating the malignant potential.

Predictive Significance of Two MMP-9 Promoter Polymorphisms and Acetylated c-Jun Transcription Factor for Papillary Thyroid Carcinoma Advancement.

Papillary thyroid carcinoma represents a challenge from a prognostic standpoint. Molecular alterations responsible for PTC advancement include MMP-9 genetic promoter polymorphisms that bind transcription factors with varying degrees of affinity and, hence, constitute a predisposition for MMP-9 expression. We examined how two promoter polymorphisms (the -1562 C/T transition and -131 (CA)n tandem repeats) as well as levels of the c-Jun transcription factor and its modified form acetylated at Lys271 influence MMP-9 expression and PTC progression. A significant proportion of PTC samples were heterozygous for the (CA)n tandem repeat number, had a transcription-promoting T allele at -1562, and expressed high levels of c-Jun, acetylated c-Jun, and MMP-9 protein. The T allele at the -1562 position accompanied the elevated MMP-9 protein expression, while high acetylated c-Jun levels accompanied the high MMP-9 protein levels on mRNA. The -1562 C/T transition, MMP-9, and acetylated c-Jun were associated with the presence of extra-thyroid invasion and degree of tumor infiltration, while the T allele and acetylated c-Jun also correlated with tumor stage. We conclude that the -1562 MMP-9 polymorphism and levels of acetylated c-Jun affect PTC progression via modulation of MMP-9 levels. Genotyping the MMP-9 at -1562 and estimating the levels of MMP-9 and acetylated c-Jun in PTC may prove beneficial in identifying high-risk patients.

Major Aortic Reconstruction with the Replacement of Supra-Aortic Branches: Successful Surgical Treatment of Takayasu Arteritis Initially Presented as Congestive Heart Failure.

Takayasu arteritis (TA) is a rare, large vessel vasculitis that affects aorta, its major branches, and occasionally pulmonary arteries. Patients with TA can present with constitutional features and/or various symptoms and signs caused by morphological changes in the blood vessels affected by the inflammatory process. Corticosteroids (CS) and immunosuppressives (IS) are the first line treatment for active TA. Open surgery remains a treatment of choice for TA patients with moderate-to-severe aortic regurgitation (AR) and ascending aortic aneurysm (AAA). We present a 26-year-old female diagnosed with an advanced stage of TA, initially presented as congestive heart failure. Due to a progressive course of the disease (AR 3+, AAA 5.5 cm), surgery of the Aortic valve and root (Bentall procedure), with total arch reconstruction and replacement of supra-aortic branches was performed. The patient has had an uneventful recovery during the postoperative course with no complications at one year follow-up. Normal left ventricle (LV) diameter, LV ejection fraction 67%, and a trace of AR were seen on the last echocardiography.

Successfully Resected Cardiac Metastatic Melanoma in a Lifesaving Cardiac Surgery: A Case Report.

INTRODUCTION: Metastatic tumors are the most frequent tumors of the heart with the melanoma metastasis being the most frequent. In cases of a cardiac tamponade or a low cardiac output syndrome due to the position of the tumor it could lead to an acute life-threatening condition for the patient. CASE REPORT: We present a case of a successfully treated metastatic cardiac melanoma in a lifesaving cardiac surgery. A 42-year-old woman was admitted to the emergency department of the Clinical Center of Serbia in a critical state with signs of tricuspid orifice obstruction with a tumor mass. Her previous medical history showed that she had an adequate surgical excision of the melanoma in the right lumbar region at the age of 39. An emergency cardiac surgery was performed with the resection of the tumor and the atrial wall. The postoperative course was uneventful and a HP exam once again confirmed the same type of melanoma as previously diagnosed. The patient was alive and well on follow-up exams for 4 months when she was diagnosed with metastatic tumor masses in the pelvis with ascites and melanosis of the entire skin followed by lethal outcome 5 months after the cardiac surgery. CONCLUSION: Surgical resection of metastatic cardiac melanoma can be safe and effective in an emergency scenario, especially in the case of solitary metastasis. It can be performed with excellent results and very few postoperative complications. However, due to the nature of the principal disease, the long-term survival rate remains low, giving the surgery a place in palliative treatment.

MMP-9-1562 C/T single nucleotide polymorphism associates with increased MMP-9 level and activity during papillary thyroid carcinoma progression.

Papillary thyroid carcinoma (PTC), a common form of thyroid malignancy, displays significant variations in clinical features and outcome. The malignant transformation of the thyroid is driven by altered expression of many matrix-modulating enzymes, including matrix metalloproteinase-9 (MMP-9). A single nucleotide polymorphism in its promotor (-1562 C/T) is suspected to cause overexpression of MMP-9, which in turn contributes to development of a tumour unfavourable phenotype. The aim of this study was to investigate the impact of MMP-9 promotor genotype on MMP-9 expression in PTC samples, and to assess its value as a possible risk factor for developing PTC or its aggressive phenotype. A total of 105 PTC patients and 43 healthy controls were genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. In order to estimate MMP-9 expression, PTC tissue sections were stained immunohistochemically. Statistical analysis showed that PTC cases and controls did not differ significantly in genotype frequencies (OR = 2.27, CI = 0.854-6.022). In PTC samples, the presence of the T allele was accompanied by elevated MMP-9 expression (p = 0.047) as well as a higher risk of developing extrathyroid extensions (p = 0.037) and high TNM stages (p = 0.009). Moreover, we observed overexpression of MMP-9 in cases presenting with extrathyroid invasion (p = 0.001), lymph node metastasis (p = 0.028), large tumour size (p = 0.031) and advanced stage (p = 0.005) compared to indolent tumours, along with enhanced enzymatic activity demonstrated by in situ zymography. Data suggests that MMP-9 (-1562 C/T) does not facilitate predisposition for PTC but affects the disease course by modulating MMP-9 expression. Genotyping MMP-9 provides important information which may prove beneficial in risk stratification of PTC patients.

Inverse expression of caveolin-1 and EGFR in thyroid cancer patients.

Cytological analysis of fine-needle aspiration (FNA) is the first step in evaluation of patients with nodular thyroid disease with the primary goal to exclude thyroid malignancy. Its improvement by combining cytology with molecular markers is still a matter of investigation. In this study, 2 molecular markers were used: caveolin-1 and epidermal growth factor receptor (EGFR), along with the well-established genetic marker BRAF V600E mutation. We set out to determine the expression signatures of EGFR and caveolin-1 in patients with thyroid malignancy as well as to determine their possible association with disease severity. In FNA biopsy samples (n=186), immunocytochemical expression of caveolin-1 and BRAF V600E mutation coincided with malignancy. The patients were sorted according to 3 parameters: final histopathological diagnosis, caveolin-1 expression, and BRAF V600E mutation status before measurement of EGFR mRNA expression. EGFR upregulation was detected in the group of patients with malignant diagnosis, no caveolin-1 expression, and wild-type BRAF. Spearman rank correlation yielded a statistically significant negative correlation of EGFR and caveolin-1. Double immunofluorescence confirmed colocalization and inverse expression of EGFR and caveolin-1. Our data demonstrated that EGFR overexpression is associated with malignancy but not with tumor aggressiveness. Furthermore, high-caveolin-1/low-EGFR cases were associated with an advanced pT status and had a greater degree of neoplastic infiltration than low-caveolin-1/high-EGFR cases. Combining caveolin-1 and BRAF V600E with EGFR might help in recognizing more aggressive thyroid lesions in a pool of relatively indolent tumors in FNA biopsies and thus be useful for early risk stratification of thyroid cancer patients.

Giant Posttraumatic Cervical Hematoma: Acute Presentation of Papillary Thyroid Carcinoma in an Adolescent.

OBJECTIVE: To describe a rare case of acute presentation of papillary thyroid carcinoma (PTC). CLINICAL PRESENTATION AND INTERVENTION: A 19-year-old male presented with an expanding cervical mass following blunt trauma. A computed tomography scan revealed a mass suspected to be hematoma that was compressing the vessels and thereby deviating the trachea. Immediate surgery was performed. Neither vascular injury nor active bleeding was seen; instead, a solid, hematoma-like tumefaction in the right thyroid lobe was revealed. A total thyroid lobectomy was performed. A histologic paraffin section confirmed a PTC that was permeated by hematoma. CONCLUSION: This was a unique case of an acute, life-threatening presentation of previously asymptomatic PTC in an adolescent.

Stomatin-like protein 2 overexpression in papillary thyroid carcinoma is significantly associated with high-risk clinicopathological parameters and BRAFV600E mutation.

Stomatin-like protein 2 (SLP-2), a member of the stomatin protein family, has emerged as a potential molecular hallmark of tumor progression in several human malignancies. The aim of this study was to analyze SLP-2 expression pattern in benign and malignant thyroid tumors (n = 210) and to examine its relationship with clinicopathological parameters and BRAFV600E mutation in thyroid cancer. SLP-2 immunohistochemical expression was not detected in benign adenomas and was absent/weak in follicular and anaplastic carcinomas. High expression levels of SLP-2, found only in papillary thyroid carcinoma (PTC), particularly in the classical variant, were significantly associated with adverse clinicopathological parameters: lymph node metastasis (p = 0.002), extrathyroid invasion (p < 0.001), pT status (p < 0.001), and advanced tumor stage (p = 0.001). Additional genotyping of PTC cases for the BRAFV600E mutation revealed for the first time a close relation between SLP-2 overexpression and the presence of BRAF mutation (p = 0.02) with high positive rates of lymph node metastasis (70%) and extrathyroid invasion (80%) in these cases. The significant association of SLP-2 overexpression with unfavorable clinicopathological characteristics and BRAFV600E mutation indicates that SLP-2 may have a role in aggressiveness of BRAF-mutated PTC and that SLP-2 evaluation could be clinically useful in identification of high-risk PTC patients.

Defining the value of CD56, CK19, Galectin 3 and HBME-1 in diagnosis of follicular cell derived lesions of thyroid with systematic review of literature.

BACKGROUND: Nodular follicular lesions of thyroid gland comprise benign and malignant neoplasms, as well as some forms of hyperplasia. "Follicular" refers to origin of cells and in the same time to growth pattern - building follicles. Nodular follicular thyroid lesions have in common many morphological features, therefore attempts were made to define additional criteria for distinction between follicular adenoma, follicular carcinoma and follicular variant of papillary carcinoma. Increasing number of immunohistochemical markers is in the continual process of evaluation. METHODS: Tissue microarrays incorporating, total 201 cases, out of which 122 malignant and 79 benign follicular lesions, including neoplastic and non-neoplastic, were constructed and immunostained with antibodies to CD56, CK19, Galectin-3, HBME-1. Tissue cores were exclusively being acquired from tumour/lesion on interface with normal thyroid tissue. A systematic review of literature was done for period from the year 2001 to present time. RESULTS: All analysed markers may make a difference between benign lesions/tumours from differentiated thyroid carcinomas (p = <0.01, for all markers). Expression of all markers is significantly higher in papillary carcinoma than in follicular adenoma (p < 0.01). Statistically significant difference in expression of Galectin-3 and CD56 between follicular carcinoma and follicular adenoma was registered (p = 0.043; p = 0.028, respectively). The only marker which expression showed statistically significant difference between adenoma and carcinoma of Hurthle cells was Galectin 3 (p = 0.041). CK19 and HBME-1 were significantly expressed more in papillary carcinoma as compared to follicular carcinoma. CONCLUSION: Galectin 3 is most sensitive marker for malignancy, while loss of expression of CD56 is very specific for malignancy. Expected co-expression for combination of markers in diagnosis of follicular lesions decreases sensitivity and increases specificity for malignancy.

Malignant risk stratification of thyroid FNA specimens with indeterminate cytology based on molecular testing.

BACKGROUND: Fine-needle aspiration (FNA) has been employed for many years for examining thyroid nodules, and the cytology of aspirates is the primary determinant for whether thyroidectomy is indicated. Fifteen to thirty percent of thyroid nodules, not being clearly benign or malignant, fall into an indeterminate category. The main goals of molecular diagnostics for thyroid nodules are to prevent unnecessary surgery in patients with benign nodules and to stop patients with malignant nodules from being subjected to repeated operations. METHODS: This study was designed to evaluate the diagnostic utility of 4 markers in thyroid FNA cytology via testing for the BRAF V600E mutation and the expression of microRNA-221, microRNA-222, and galectin-3 protein in FNA samples with indeterminate cytology. RESULTS: A predictor model distinguishing benign samples from malignant samples on the basis of the 4 aforementioned markers was formulated. This decision model provided a sensitivity of 73.5%, a specificity of 89.8%, and a diagnostic accuracy of 75.7%. The positive predictive value was 80.6%, and the negative predictive value was 85.5%; this suggested that the prediction had good reliability. CONCLUSIONS: One hundred twenty FNA samples were examined, and 62 nodules were classified as benign with the proposed diagnostic algorithm. This resulted in a reduction of the initial 120 patients to 58 and thus decreased by half the number of persons undergoing surgery.

Strong expression of HBME-1 associates with high-risk clinicopathological factors of papillary thyroid carcinoma.

Thyroid cancer comprises a heterogeneous group of lesions with great diversity of biological behaviour. Markers which could help clinicians to identify high-risk patients for tailored optimization of clinical management are of crucial importance. HBME-1 protein level was analysed immunohistochemically using routinely prepared archival tissue sections of a broad range of papillary thyroid carcinoma (PTC) variants and in corresponding lymph node metastases (LNM). The results were evaluated in comparison with clinicopathological features of PTC. Positive immunoreaction was noticed in most classical (83/92; 90.2 %), follicular (60/71; 84.5 %) and trabecular (4/5; 80.0 %) variants of PTC. All cases of macrofollicular, Warthin-like and diffuse sclerosing PTC variants were HBME-1 positive (4/4, 3/3, 2/2; 100 % respectively). Tall cell and solid PTC variants showed diversity of staining (2/3; 66.67 % and 13/23; 56.52 % respectively), while PTCs with mixed histological pattern containing insular areas were mainly weakly positive (2/5; 40.0 %). A single case of clear cell PTC variant showed no reaction. Moreover, all matched metastatic PTC into lymph nodes (LNM) were HBME-1 positive (17/17; 100 %) and expressed HBME-1 in a similar pattern to the matched primary tumour. We also found a statistically significant association between high HBME-1 expression and the presence of lymph node metastasis, advanced pT status and pTNM stage (P < 0.05), but only a tendency for association with extrathyroidal invasion of the tumour (P = 0.058). Therefore, we recommend using immunoexpression of HBME-1 as useful mean to increase the likelihood of detecting most PTC variants and to predict some unfavourable clinical parameters in these patients.

Ruptured giant mitral valve aneurysm: an unexpected finding in a diabetic patient with dyspnea and new-onset atrial fibrillation.

Mitral valve aneurysm (MVA) is a rare valve disease. The case is reported of pathologically proven MVA in a 61-year-old diabetic male with chronic alcoholic liver disease who presented with dyspnea and new-onset atrial fibrillation, without clinical elements of current or recent infection. Transthoracic echocardiography revealed a 'cystic' formation of the anterior mitral leaflet (AML) with mild mitral regurgitation (MR) and aortic regurgitation (AR) hitting the AML. Transesophageal echocardiography (TEE) showed clearly that the formation on the AML was a valve aneurysm, and depicted the site of aneurysm rupture with an additional jet of MR through the rupture. Following mitral valve replacement, pathology of the excised valve showed chronic bacterial endocarditis with calcified bacterial colonies, myxomatous changes with fibrinoid dissection of lamina fibrosa, and neovascularization of the leaflet. The mechanisms of MVA formation are discussed, together with its potential complications, diagnostic modalities and therapeutic strategies. The present case emphasizes that MVA is often a remnant of endocarditis, even when the latter is clinically silent and undiagnosed. The importance of chronic AR directed towards the AML as a predisposing condition for MVA formation is also underlined in this case. The superiority of TEE in providing a full exploration of the mitral valve morphology is verified.

Influence of the chronic abdominal aortic occlusion on the femoral artery disease pattern.

We design a study to evaluate whether patients with chronic aortic occlusion have a different pattern of femoral artery atherosclerosis than patients with other forms of aortoiliac disease as well as to discuss potential causal mechanisms. From January 2008 to January 2010, 467 patients with aortoiliac occlusive disease were enrolled at Clinic of Vascular and Endovascular Surgery in Belgrade, Serbia. Among them 60 patients were divided into two groups, patients with chronic aortic occlusion (COA) and diffuse aortoiliac occlusive disease (AIOD, Leriche type II). Each group consisted of 30 patients. Those two groups were compared according to symptomatology, ABI values, femoral artery pressure gradient, atherosclerosis level in the femoral region and predictors of atherosclerosis.Patients with AIOD had severe atherosclerosis unlike patients with COA. Also, high elevation of postoperative ABIs in patients with an early atherosclerosis (0, I, II and III) was noted suggesting patent distal arterial tree. FAP gradient was significantly higher in COA group comparing with AIOD group (left: t=-10.963, P<0.01;right: t=-8.962, P<0.01). In conclusion, our data demonstrate that older patients have had more time to develop multilevel disease (AOID) and those with CAO have more isolated aortic disease chronic aortic occlusion.

Right ventricular myxoma - a case report.

INTRODUCTION: Myxomas arising from the right ventricle are extremely rare. CASE REPORT: We presented a 71-year-old patient with worsening symptoms of the exertional dyspnea and atypical chest pains lasting 6 months. A transthoracic and transesophageal echocardiogram revealed a large, 2.6 x 2.2 cm, ovoid, well-circumscribed, echogenic mass in the right ventricle outflow tract attached by small pedicle, partly obstructing the right ventricular outflow tract and protruding through the pulmonic valve during systole. The tumor was completely removed with the stalk and 5 mm of the surrounding tissue. The histopathological findings confirmed the diagnosis of myxoma. CONCLUSION: This case illustrates the usefulness of echocardiography both in diagnosis of patients with atypical symptoms without family history and associated syndromes (like Carney's complex), and in surgical approach planning. It also stresses the importance of surgical excision of tumor as soon as possible following the diagnosis to prevent the complications such are: valvular obstruction, pulmonary embolization and syncopes.

Caveolin-1 expression in thyroid neoplasia spectrum: comparison of two commercial antibodies.

We evaluated caveolin-1 expression in the human thyroid neoplasia spectrum with the aim of examining differences in expression as detected by two anti-caveolin-1 antibodies, and secondly, to investigate the association of caveolin-1 expression levels with aggressive papillary thyroid carcinoma (PTC). Immunohistochemical staining using sc894 or AV09019 antibodies revealed that caveolin-1 was generally overexpressed in the PTC group as a whole (classical and follicular variant) when compared to peritumoral tissue (PT), while it was not detected in about half of follicular thyroid carcinoma (FTC) and majority of follicular adenomas (FTA). Caveolin-1 expression decreased in the following order: clPTC, fvPTC, FTC, PT and FTA. The diagnostic accuracy of AV09019 was better than that of sc894 for discriminating: FTA from FTC, FTA or FTC from the follicular variant of PTC, total PTC from nonmalignant tissue, and malignant tumors from nonmalignant tissue. Spearman's analysis revealed positive correlations of caveolin-1 expression and extrathyroidal invasion (p< 0.05) in PTC for both antibodies. Additionally, AV09019 antibody correlated caveolin-1 upregulation with pathological T status. To conclude, as an immunohistochemical marker AV09019 antibody performed better than sc894 in distinguishing certain histotypes of thyroid tumors. In addition, increased expression of caveolin-1 may be considered as an indicator of papillary carcinoma progression.

[Pheochromocytoma--pathohistologic and immunohistochemical aspects]. / Feohromocitom--patohistoloski i imunohistohemijski aspekti.

INTRODUCTION: Pheochromocytoma originates in chromaffin cells of the adrenal medulla. Its incidence is similar in both sexes and most frequent between the ages of thirty and fifty. Multiple and bilateral pheochromocytomas constitute 5 to 10 percent of all cases. Pheochromocytoma occurs sporadically or is related to family syndromes such as: syndrome of multiple endocrine neoplasia--MEN IIA and IIB, neurofibromatosis (von Recklinghausen's disease), von Hippel-Lindau's disease, Sturge-Weber's syndrome, and tuberous sclerosis. Cases in a family usually occur at a younger age and are mostly bilateral and with more aggressive biological behaviour. MATERIAL AND METHODS: The aim of the study was to make histomorphological and immunohistochemical analyses of 52 pheochromocytomas. These cases are the surgical material from the Centre of Endocrine Surgery, Institute of Endocrinology, Diabetes, and Metabolic Disorders, Clinical Centre of Serbia, Belgrade, over the period from 1974 to 1997. Frozen and fixed sections, which were cut from paraffinembedded material and stained by both hematoxylin-eosin and PAS, were used in order to make pathohistological diagnoses. The expression of chromogranin A, S-100 protein and ACTH was examined using the PAP method, while neuronspecific enolase (NSE), synaptophysin and neurofilament were examined by the APAAP method with appropriate antibodies (DAKO). RESULTS: The patients were between 4 and 65 years of age (average age 38.5) and there were 28 females (63.64%) and 16 males (36.36%). The largest pheochromocytoma had the diameter of 12 cm, and weight of pheochromocytomas in question was from 13.5 to 370 grams, the average weight being 83.4 grams. On gross examination, the tumours proved to be well-defined, either by fibrous capsule, or by adrenocortical tissue. The cross-sections of tumours were mainly of pale red-grayish colour, and showed numerous foci of necrosis, haemorrhage and cystic softening. Histological appearance of pheochromocytomas was with significant irregularities in shapes and dimensions of the cells and their patterns. Pheochromocytes were mostly of polygonal shape (45 cases, 86.54%), whereas in 7 cases (13.46%) fusiform cells were evident. Cells were arranged, either in trabeculae intermingled with thin-walled sinusoids, or in small alveolae circumferenced by fibrovascular stroma. PAS positive hyaline globules were often present in the cell cytoplasm and also extracellularly. Cellular and nuclear pleomorphism, binuclear and multinuclear cells, as well as giant cells were evident in 35 (67.31%) pheochromocytomas. Mytotic figures were infrequent in 50 tumours (one to two on ten microscopic high power fields). Malignant pheochromocytomas (2 cases) metastasized to regional lymph nodes and liver, and lungs and bones, respectively. Pheochromocytomas were associated with MEN IIA syndrome in 6 patients (13.63%), all of whom had bilateral adrenalectomy, and in the period from two months to one year later underwent total thyroidectomy due to medullar thyroid carcinoma. Simultaneous occurrence of adrenal medullar hyperplasia and pheochromocytoma, i.e. the sequence: diffuse medullar hyperplasia--nodular medullar hyperplasia -pheochromocytoma, was found in two patients with MEN IIA syndrome (33.33%). Hyperplastic nodule (1 cm in diameter) with discrete capsule and compression of surrounding adrenal tissue was considered to be a small pheochromocytoma. All the studied pheochromocytomas showed chromogranin A, NSE, and synaptophysin immunopositivity in nearly all tumour cells. Neurofilament positivity was focal and less intense. S-100 protein positive sustentacular cells were found in 29 of 32 pheochromocytomas included in immunohistochemical examinations. Incidence frequency of S-100 protein positive sustentacular cells was high in pheochromocytomas related to family syndromes and low in malignant pheochromocytomas. DISCUSSION: Numerous features of the described pheochromocytomas appear in the already published data, namely: age of occurrence, tumour weight, histological and immunohistochemical characteristics, frequent association of bilateral pheochromocytoma and MEN IIA, as well as the occurrence of adrenal medullar hyperplasia as precursor of pheochromocytoma. Immunohistochemical analysis has confirmed the importance of pan-neuroendocrine markers (chromogranin A, NSE, and synaptophysin) in pheochromocytoma diagnosing, whereas it has been that neurofilament was of less importance. High incidence frequency of S-100 protein positive sustentacular cells in pheochromocytomas related to family syndromes was also noted by other authors. CONCLUSION: Histomorphological features of benign and malignant pheochromocytomas may be similar. Histologic criteria for aggressive biological behaviour of pheochromocytoma include: insular pattern of growth, 3-5 mytotic figures on 10 microscopic high power fields and invasion of capsular lymphatics and blood vessels. Pan-neuroendocrine markers (chromogranin A, NSE, synaptophysin) may be useful in diagnosis of pheochromocytoma. Incidence frequency of S-100 protein positive sustentacular cells is high in pheochromocytomas related to family syndromes and low in malignant sporadic pheochromocytoma.