Congenital thymoma

Thymomas are a heterogeneous group of tumors arising from the epithelium of the thymus. They are categorized by the proportion of neoplastic epithelia to lymphocytes and by the degree of cytologic atypia. Thymomas constitute 0.2-1.5% of all malignancies and nearly all occur in patients over 20 years. We reviewed the available literature and found less than 50 cases of thymoma reported in children (<18 years of age), the youngest being 4 years old, and no cases in newborns. They represent less than 1% of all mediastinal tumors in children. Due to the limited number of cases in the pediatric population, the diagnosis and treatment in this population is extremely challenging. Thymomas in all age groups may be associated with paraneoplastic syndromes, being myasthenia gravis the most common, which is associated with a worse prognosis in the pediatric population. We present the first case of a newborn infant with congenital thymoma. This case demonstrates a rare tumor in an unusual age group and emphasizes the importance of multidisciplinary teamwork in the decision-making and management of this condition.

[Congenital anomalies of thymic origin in the neck]. / Anomalías congénitas de origen tímico en el cuello.

RATIONALE: A symptomatic mass in the thymus is due to anomalies in the development of the pharyngeal pouches and is also an unusual cause of consultation. These anomalies may be found anywhere along the natural path of the embryonic thymus, from the angle of the jaw to the upper mediastinum. AIM: To review the epidemiology, pathogenesis, diagnosis, and management of congenital anomalies of thymic origin in the neck. MATERIAL AND METHOD: A MEDLINE search was carried out, using the Cochrane methodology, for articles published from January 1980 to January 2007 using the terms "thymus gland," "cervical mass." Following this bibliographical search, the texts considered most relevant by the authors were selected. CONCLUSIONS: While this anomaly is relatively common, its level of presentation is very low and it should always be considered in the differential diagnosis of congenital masses in the neck. New diagnostic imaging techniques provide an early and more accurate diagnosis, thus allowing a better outcome in these patients.

Anomalías congénitas de origen tímico en el cuello / Congenital anomalies of thymic origin in the neck

Justificación: La masa tímica sintomática en el cuello se debe a anomalías en el desarrollo de las bolsas faríngeas y es una causa inusual de consulta. Estas anomalías se pueden encontrar a lo largo de la vía embriológica de descenso del timo, desde el ángulo de la mandíbula hasta el mediastino superior. Objetivo: Realizar una revisión estructurada de la epidemiología, la patogenia, el diagnóstico y el tratamiento de las masas congénitas de origen tímico en el cuello. Material y método: Se realizó una búsqueda en MEDLINE, según la metodología Cochrane, de artículos publicados desde enero de 1980 a enero de 2007 usando los términos “thymus gland” y “cervical mass”; los autores seleccionaron de esta búsqueda los manuscritos que consideraron relevantes. Conclusiones: Aunque esta anomalía es relativamente común, su presentación clínica es poco frecuente; siempre se debe considerar en el diagnóstico diferencial de las masas congénitas en el cuello. Las nuevas técnicas de imágenes facilitan un diagnóstico precoz y más preciso, lo que permite un mejor pronóstico para estos pacientes

Rationale: A symptomatic mass in the thymus is due to anomalies in the development of the pharyngeal pouches and is also an unusual cause of consultation. These anomalies may be found anywhere along the natural path of the embryonic thymus, from the angle of the jaw to the upper mediastinum. Aim: To review the epidemiology, pathogenesis, diagnosis, and management of congenital anomalies of thymic origin in the neck. Material and method: A MEDLINE search was carried out, using the Cochrane methodology, for articles published from January 1980 to January 2007 using the terms “thymus gland,” “cervical mass.” Following this bibliographical search, the texts considered most relevant by the authors were selected. Conclusions: While this anomaly is relatively common, its level of presentation is very low and it should always be considered in the differential diagnosis of congenital masses in the neck. New diagnostic imaging techniques provide an early and more accurate diagnosis, thus allowing a better outcome in these patients

Fetal mouse Cyp1b1 and transplacental carcinogenesis from maternal exposure to dibenzo(a,l)pyrene.

Dibenzo(a,l)pyrene (DBP) is among the most potent carcinogenic polycyclic aromatic hydrocarbons. Previously, we showed that DBP administration to pregnant mice resulted in high mortality of offspring from an aggressive T-cell lymphoma. All mice that survive to 10 months of age exhibit lung tumors with high multiplicity. Recombinant cytochrome P450 (cyp) 1b1 from mice and the homologue 1B1 in humans exhibit high activity toward the metabolic activation of DBP. Targeted disruption of the cyp1b1 gene protects against most DBP-dependent cancers. Mice heterozygous for the disrupted cyp1b1 allele were used to examine the effect of cyp1b1 gene dosage on DBP transplacental carcinogenesis. Dams were treated with 1 or 15 mg/kg of DBP or 50 mg/kg of benzo(a)pyrene. Cyp1b1-null offspring did not develop lymphoma, whereas wild-type and heterozygous siblings, born to dams given the high dose of DBP, exhibited significant mortalities between 10 and 30 weeks of age. At 10 months, all groups had lung adenomas or carcinomas [9.5%, 40.3%, 25.6%, and 100% incidences for controls, benzo(a)pyrene, 1 and 15 mg/kg DBP, respectively]. Cyp1b1 status did not alter benzo(a)pyrene-dependent carcinogenesis. At 1 mg/kg DBP, cyp1b1 status altered the incidence of lung tumors (19.0, 27.8, and 28.6% for nulls, heterozygous, and wild-type, respectively). At 15 mg/kg, tumor multiplicities in cyp1b1 wild-type (9.3) and heterozygous (9.5) offspring were nearly twice that of cyp1b1-null siblings (5.0). These data confirm that cyp1b1 bioactivation of DBP occurs in fetal target tissues, following transplacental exposure, with the thymus and lung as primary and secondary targets, respectively.

[Tracheobronchial compression by congenital tumors]. / Les compressions trachéo-bronchiques par tumeurs congénitales.

The writer reports on 21 observations of congenital cervicomediastinal tumors with respiratory distress by tracheo-bronchic compression (7 cystic hygromas, 4 hemangiomas, 8 teratomas, 2 thymic cysts), and review the literature about: frequence of respiratory troubles caused by these tumors (44% among benign mediastinal tumors, younger than 2 years child); and their etiopathology: tracheal compression by tumor (cystic hygroma, teratoma), tracheal invasion (hemangioma), post surgical tracheomalacia, nervous lesions; diagnostic (Xray, TDM, endoscopy) and therapeutic (intubation, tracheostomy) accessments in pre and postoperative periods.

Progressive neonatal airway obstruction secondary to cervical thymic cyst.

Cervical thymic cysts are extremely unusual neoplasms that only rarely produce signs and symptoms of upper airway tract compromise. Less than 7% of patients initially have dyspnea or hoarseness. We report the first known case of progressive neonatal airway obstruction secondary to a rapidly enlarging cervical thymic cyst. Because one half of these benign tumors may demonstrate mediastinal extension, computed axial tomography or B-mode ultrasonography or both is recommended prior to surgical excision. Review of the literature confirms that the majority are successfully removed via a transcervical approach without recurrence.

Symptomatic cervical thymic cyst in a neonate.

Thymic cysts are unusual neck masses in adults and children and are rarely differentiated from other neck masses by physical examination. This is a case report of a thymic cyst producing airway obstruction in a neonate. The embryogenesis and differential diagnosis of thymic cysts are reviewed.