Michel Wassef

Vascular Anomalies Classification: Recommendations From the International Society for the Study of Vascular Anomalies

Vascular anomalies represent a spectrum of disorders from a simple “birthmark” to life- threatening entities. Incorrect nomenclature and misdiagnoses are commonly experienced by patients with these anomalies. Accurate diagnosis is crucial for appropriate evaluation and management, often requiring multidisciplinary specialists. Classification schemes provide a consistent terminology and serve as a guide for pathologists, clinicians, and researchers. One of the goals of the International Society for the Study of Vascular Anomalies (ISSVA) is to achieve a uniform classification. The last classification (1997) stratified vascular lesions into vascular malformations and proliferative vascular lesions (tumors). However, additional disease entities have since been identified that are complex and less easily classified by generic headings, such as capillary malformation, venous malformation, lymphatic malformation, etc. We hereby present the updated official ISSVA classification of vascular anomalies. The general biological scheme of the classification is retained. The section on tumors has been expanded and lists the main recognized vascular tumors, classified as benign, locally aggressive or borderline, and malignant. A list of well-defined diseases is included under each generic heading in the “Simple Vascular Malformations” section. A short definition is added for eponyms. Two new sections were created: one dealing with the malformations of individually named vessels (previously referred to as “truncular” malformations); the second groups lesions of uncertain or debated nature (tumor versus malformation). The known genetic defects underlying vascular anomalies are included in an appendix. This classification is meant to be a framework, acknowledging that it will require modification as new scientific information becomes available.

Rapidly Involuting Congenital Hemangioma: Clinical and Histopathologic Features

We define the histopathologic findings and review the clinical and radiologic characteristics of rapidly involuting congenital hemangioma (RICH). The features of RICH are compared to the equally uncommon noninvoluting congenital hemangioma (NICH) and common infantile hemangioma. RICH and NICH had many similarities, such as appearance, location, size, and sex distribution. The obvious differences in behavior served to differentiate RICH, NICH, and common infantile hemangioma. Magnetic resonance imaging (MRI) of the three tumors is quite similar, but some RICH also had areas of inhomogeneity and larger flow voids on MRI and arterial aneurysms on angiography. The histologic appearance of RICH differed from NICH and common infantile hemangioma, but some overlap was noted among the three lesions. RICH was composed of small-to-large lobules of capillaries with moderately plump endothelial cells and pericytes; the lobules were surrounded by abundant fibrous tissue. One-half of the specimens had a central involuting zone(s) characterized by lobular loss, fibrous tissue, and draining channels that were often large and abnormal. Ancillary features commonly found were hemosiderin, thrombosis, cyst formation, focal calcification, and extramedullary hematopoiesis. With one exception, endothelial cells in RICH (as in NICH) did not express glucose transporter-1 protein, as does common infantile hemangioma. One RICH exhibited 50% postnatal involution during the 1st year, stopped regressing, was resected at 18 months, and was histologically indistinguishable from NICH. In addition, several RICH, resected in early infancy, also had some histologic features suggestive of NICH. Furthermore, NICH removed early (2–4 years), showed some histologic findings of RICH or were indistinguishable from RICH. We conclude that RICH, NICH, and common infantile hemangioma have overlapping clinical and pathologic features. These observations support the hypothesis that these vascular tumors may be variations of a single entity ab initio. It is unknown whether the progenitor cell for these uncommon congenital vascular tumors is the same as for common infantile hemangioma.

Biological Determinants of Aldosterone-Induced Cardiac Fibrosis in Rats

To determine the events leading to cardiac fibrosis in aldosterone-salt hypertensive rats, we studied protein and mRNA accumulation of procollagens I and III for 60 days. After 3 and 7 days of treatment systolic pressure was normal, and no histological or biochemical changes were seen in rat hearts. At day 15 arterial pressure was raised (+40%) and left ventricular hypertrophy was +15%. Cardiac examination after hemalun-eosin staining and immunolabeling with anticollagen I and III antibodies showed no structural alterations, but an 83% increase in right ventricular type III procollagen mRNA levels was found. At 30 and 60 days we found progressive cardiac fibrosis, with inflammatory cells, myocyte necrosis, and elevation of both types I and III procollagen mRNA levels in both ventricles. To determine whether aldosterone had effects on Na,K-ATPase that might lead to ionic disturbances and induce myocyte necrosis, we studied the major cardiac Na,K-ATPase isoform genes. Although Na,K-ATPase alpha 1- and beta 1-subunit mRNA levels were elevated in kidney at day 1, neither of these cardiac transcripts nor the specific alpha 2 isoform was altered between 1 and 15 days. These results show that accumulation of procollagen mRNAs occurs before collagen deposition. Cardiac alterations are late and not preceded by changes in Na,K-ATPase cardiac gene expression, precluding a direct modulation of cardiac collagen synthesis and Na,K-ATPase by aldosterone.

Coagulation Disorders in Patients With Venous Malformation of the Limbs and Trunk: A Case Series of 118 Patients

OBJECTIVE To investigate the clinical characteristics of venous malformation of the limbs and trunk and known but poorly appraised associated coagulation disorders. Venous malformations are ubiquitous, slow-flow vascular anomalies known to be occasionally painful because of thrombotic episodes inside the lesion. DESIGN Large case series, with screening of accepted standard coagulation tests. SETTING Ambulatory multidisciplinary clinics for vascular anomalies. PATIENTS This 2-year study (2003-2005) included 118 patients with clinical, radiological, and biological features informative for better defining venous malformation and associated coagulation abnormalities. MAIN OUTCOME MEASURES The primary outcome was coagulation disorders associated with VM. Secondary measures include anatomic location, extent of lesion, localized pain, and impaired motion. RESULTS The mean age of patients was 27 years, and there was a female preponderance of 64%. The venous malformation involved the upper extremity, lower extremity, and trunk in 30%, 58%, and 36% of patients, respectively; it was plurifocal in 22%. Intralesional pain (in 92% of patients) had a higher frequency in female (63%) than in male (47%) patients. Tissular involvement concerned the skin (65%), muscle (73%), bone (13%), joints (12%), and viscera (9%). According to our severity scoring system, cases of less gravity had a score of 2 or 3 (52%), cases of intermediate severity had a score of 4 or 5 (32%), and cases of major severity had a score of 6 to 9 (10%). The most frequent blood coagulation abnormality was a high plasma D-dimer level (> 0.5 microg/mL) (58% of patients), which was correlated with muscle involvement and high severity score and was more frequent in women. The factor VIII-von Willebrand factor complex was documented in 84 patients, and plasma von Willebrand factor level was decreased (<60%) in 23 (27%) of them; 10 of the 84 patients (12%) had more notably decreased levels (<50%). CONCLUSIONS This study of a large case series of patients with pure venous malformation in the limbs and/or trunk highlights muscle involvement and frequency of pain. It validates that coagulation disorders, present in 58% of our patients, create thrombotic painful events. Under certain circumstances, these disorders entail a risk of hemorrhage because of the progression of localized intravascular coagulopathy to disseminated intravascular coagulopathy.

Embolization of hepatocellular carcinoma with drug-eluting beads: Doxorubicin tissue concentration and distribution in patient liver explants

BACKGROUND & AIMS To follow the local tissue delivery of doxorubicin in HCC explants from patients embolized with drug-eluting beads and to compare it with histologic modifications. METHODS Six patients with HCC underwent chemoembolization with doxorubicin-eluting beads (caliber 100-300 μm, dose 75-150 mg) followed by liver transplantation at different time points (8 h to 36 days). On sections of the explanted liver, the tissue concentration of doxorubicin was determined radially around bead-occluded vessels with microspectrofluorimetry. The intra/peritumoral location of the beads and the modifications of the surrounding tissue were determined on an adjacent hematein-eosin-saffron-stained section and compared to drug measurements. RESULTS Doxorubicin was detected in the tissue surrounding the beads at all times of explantation. The drug impregnates an area of at least 1.2 mm in diameter around the occluded vessel. The tissue concentration of drug ranges from 5 μM at 8 h to 0.65 μM at 1 month. In patient transplanted at 8 h, no major tissue modification was observed and we found 42% of the beads occluding intratumoral vessels. Drug concentration was not different around intratumoral and peritumoral occluded vessels. After 9-14 days, necrosis was present around 37% of vessels and at 32-36 days, around 40% of vessels. Necrotic tissue was associated with a deeper penetration and a higher concentration of the drug than non necrotized areas, though statistically significant only at 32-36 days. CONCLUSIONS Doxorubicin-eluting beads provide a sustained delivery of drug for a period of 1 month and local tissue concentrations above cytotoxic threshold in HCC-bearing livers.

Drug-eluting Beads for Liver Embolization: Concentration of Doxorubicin in Tissue and in Beads in a Pig Model

PURPOSE To evaluate the local tissue concentrations of the antineoplastic agent doxorubicin and the amount of drug still present inside drug delivery embolization beads at different time points after embolization and to compare doxorubicin levels with histologic modifications around the beads in a pig liver model. It was hypothesized that doxorubicin-eluting beads maintain cytotoxic concentrations of drug locally over a period of several weeks, as suggested by in vitro elution tests. MATERIALS AND METHODS Left lobe hepatic artery embolization was performed in 10 pigs with 100-300-microm or 700-900-microm beads loaded with 37.5 mg doxorubicin/mL. Control unloaded 100-300-microm beads were injected in five pigs. Livers were sampled 28 days or 90 days after embolization. The amount of drug retained inside the beads was assessed with infrared microspectroscopy. Doxorubicin concentration and distribution in the tissue around the beads were determined with microspectrofluorimetry and compared with tissue modifications on hematein eosin saffron-stained sections. RESULTS Doxorubicin-eluting beads eluted 43% of their initial drug load after 28 days and 89% after 90 days. Doxorubicin was present in tissues around the beads at both time points, with a significant decrease over time (P = .0004). The drug was detected at distances as far as 600 microm from the bead edge. Doxorubicin tissue concentrations ranged from 0.55 microM to 6.80 microM, [corrected] which are cytotoxic levels in hepatocyte cell cultures. High concentrations of drug were associated with coagulative necrosis of liver parenchyma. Doxorubicin-eluting beads 100-300 microm in size induced more necrosis than 700-900-microm beads (P = .0036). CONCLUSIONS Doxorubicin-eluting beads deliver high concentrations of the drug over a period of at least 3 months at several hundred micrometers from the bead, leading to significant cytotoxic effects.

Arterial distribution of calibrated tris-acryl gelatin and polyvinyl alcohol microspheres in a sheep kidney model.

Objective:The objective of this study was to compare the repartition in the renal arterial vasculature of tris-acryl gelatin microspheres (TGMS) and polyvinyl alcohol microspheres (PVAMS) of 3 calibers (500–700, 700–900, and 900–1200 μm). Materials and Methods:Twelve kidneys from 6 adult sheep were embolized and histologically analyzed. The number and size of microspheres and vessels were measured, as well as the deformation of TGMS and PVAMS, and the histologic location according to a classification in 5 zones of the kidney. Results:Two hundred eighty-four vessels were measured. The diameter of the occluded vessels increased when the caliber used for embolization was larger for TGMS and for PVAMS (P < 0.0001, each). The location of TGMS and PVAMS within the vasculature was different for each caliber, because PVAMS blocked significantly more distally than TGMS (P < 0.0001 each). The deformation within the tissue was greater for PVAMS (18.0 ± 12.3%) than for TGMS (9.0 ± 8.3%) in general (P < 0.001) and for each caliber of injected microspheres (P < 0.001 each). Conclusion:The repartition of a spherical embolic agent in a given vascular network can be influenced by its size and also by its deformation within the vascular bed.

Middle ear adenoma. A tumor displaying mucinous and neuroendocrine differentiation.

Middle ear adenoma (MEA) is a distinctive, rare entity that appears to be derived from the lining epithelium of the middle ear mucosa. We report four cases of MEA displaying the typical histologic growth pattern. Two distinct tumor cell immunophenotypes were identified in all cases; the first type exhibited positivity with antiepithelial membrane antigen and anti-keratin antibodies, and the second type showed immunoreactivity with antikeratin, anti-vimentin, and anti-neuron-specific enolase antibodies. Ultrastructural studies revealed bidirectional mucinous and neuroendocrine differentiation, demonstrated by the presence of two distinct cell types containing apically located mucous granules and basally concentrated neuroendocrine granules, respectively. The presence of neuroendocrine differentiation was supported by the immunohistochemical detection of vasoactive intestinal polypeptide in the tumor cells in one case and neuronspecific enolase in three cases. These findings suggests that the potential for mixed mucinous/neuroendocrine differentiation described in other endodermally derived tumors also exists in middle ear mucosa. We also believe that the rare lesions diagnosed as primary carcinoid tumors of the middle ear might in fact be MEA with predominant or only neuroendocrine differentiation. The clinical course of our four cases and our review of the pertinent literature confirm the benign nature of MEA and indicate that these tumors should be treated by complete local excision without additional therapy.

Myopic acts in the endocytic pathway to enhance signaling by the Drosophila EGF receptor

Endocytosis of activated receptors can control signaling levels by exposing the receptors to novel downstream molecules or by instigating their degradation. Epidermal growth factor receptor (EGFR) signaling has crucial roles in development and is misregulated in many cancers. We report here that Myopic, the Drosophila homolog of the Bro1-domain tyrosine phosphatase HD-PTP, promotes EGFR signaling in vivo and in cultured cells. myopic is not required in the presence of activated Ras or in the absence of the ubiquitin ligase Cbl, indicating that it acts on internalized EGFR, and its overexpression enhances the activity of an activated form of EGFR. Myopic is localized to intracellular vesicles adjacent to Rab5-containing early endosomes, and its absence results in the enlargement of endosomal compartments. Loss of Myopic prevents cleavage of the EGFR cytoplasmic domain, a process controlled by the endocytic regulators Cbl and Sprouty. We suggest that Myopic promotes EGFR signaling by mediating its progression through the endocytic pathway.

Ethacrynic acid facilitates gentamicin entry into endolymph of the rat.

Influence of ethacrynic acid (EA) upon gentamicin kinetics in perilymph and endolymph was studied in rats that were given a constant-infusion of gentamicin (150 micrograms/min) and EA (140 micrograms/min). Inner ear fluids and plasma were sampled up to 5 h. The purity of the endolymph was ensured by measurement of sodium and potassium concentrations. Gentamicin assay was done with a modified radioimmunoassay. Results show that EA facilitates the entry of gentamicin into endolymph, while it does not affect the kinetics of the drug in perilymph. Although the mechanism of this facilitation remains unclear, this result may account for the ototoxic potentiation reported between EA and aminoglycoside antibiotics.