Histologic patterns of thymic involvement in Langerhans cell proliferations: a clinicopathologic study and review of the literature.

Thymic involvement by Langerhans cell histiocytosis (LCH) has been described mainly in isolated case reports. A description of the histopathologic patterns of LCH proliferations in the thymus, together with therapeutic implications, has not, to our knowledge, been previously addressed. The pathology consultation files at Children's Hospital of Pittsburgh of the University of Pennsylvania Medical Center were reviewed for cases of thymic involvement by LCH. Relevant cases in the literature were also reviewed, and the histopathology and clinical course of those cases were collected. Nine consultation cases of thymic involvement were reviewed, together with 23 cases in the literature, which provided adequate pathologic description and ancillary confirmation (n  =  32), revealing 4 distinct pathologic groups. Group 1 showed microscopic collection of hyperplastic LCH-like cells in incidental thymectomies of patients without LCH disease, requiring no further treatment (n  =  7; 22%). Group 2 showed solitary and/or cystic LCH of the thymus with gland disruption, and at least 3 cases resolved without systemic therapy (n  =  10; 31%). Group 3 showed more variable thymic involvement in multisystemic LCH disease, with either a medullary restricted pattern or more diffuse gland involvement, requiring adjuvant therapy and having a higher mortality rate (n  =  13; 41%). Group 4 showed a mixed histiocytic lesion with a concurrent LCH and juvenile xanthogranuloma-like proliferation (n  =  2; 6%). Thymic involvement in LCH is quite rare. Based on our cases and those in the literature, we propose 4 distinct pathologic groups of thymic involvement in Langerhans cell proliferations with relevance for diagnosis and treatment.

[Management of anterior mediastinal masses in adults]. / Quelle attitude face à une masse médiastinale antérieure chez l'adulte ?

The discovery of an anterior mediastinal mass requires careful management with specific consideration of the pathology. More than 50% of all mediastinal masses seen in adults are in the anterior mediastinum. The most frequent diagnoses are thymoma, lymphoma, teratoma and benign thyroid tumours. 60% of cases are malignant. Often the clinical and radiological findings do not allow a definitive diagnosis and a histological diagnosis is often required to select the optimal treatment modality. The choice of biopsy technique depends on the localization of the lesion, clinical factors, and the availability of special techniques and equipment. Biopsy may be obtained by trans-thoracic puncture under computed tomography or ultrasound guidance, or by a surgical approach (mediastinotomy or thoracoscopy).

Mediastinal tumors and cysts in the pediatric population.

Pediatric mediastinal tumors and cysts are rare disorders that share many similarities with adults, yet which have important differences unique to the child. Posterior mediastinal tumors are relatively more common in children than in adults and are also more likely to be malignant in children. CT imaging facilitates the diagnostic evaluation of mediastinal masses in children. Airway compression is always a concern with large mediastinal tumors in children given their relative softer and smaller airway.

Rebound thymic hyperplasia after pneumonectomy and chemotherapy for primary synovial sarcoma.

Thymic hyperplasia occurs in a small proportion of patients receiving chemotherapy for various malignancies. It likely results from an immunologic rebound phenomenon. Fluorodeoxyglucose positron emission tomography-computed tomography is an important tool for staging malignant neoplasms. We report a case of rebound thymic hyperplasia manifesting as a hypermetabolic mass on fluorodeoxyglucose positron emission tomography-computed tomography after pneumonectomy and chemotherapy for primary pulmonary synovial sarcoma. We highlight the importance of recognizing the phenomenon of rebound thymic hyperplasia, as it can mimic residual or recurrent malignancy, especially in the setting of altered chest anatomy.

Myasthenia gravis with thymus hyperplasia and pure red cell aplasia.

A case of myasthenia gravis (MG) with thymus hyperplasia and pure red cell aplasia (PRCA) is reported. A 57-year-old woman was diagnosed as having MG and was treated with thymectomy 26 years ago. The histology of the resected thymus was thymic lymphoid follicular hyperplasia. She developed rapidly progressive anemia and a bone marrow examination revealed PRCA. Her hematological results improved with oral administration of cyclosporine A. Cases of MG, thymoma and PRCA have been reported in the literature. We report the first case of MG without thymoma and PRCA.

Estudio experimental de homoinjertos criopreservados: modificaciones miointimales

Objetivo. Evaluar el desarrollo de hiperplasia intimal, muerte celular y respuesta macrofágica, en injertos arteriales criopreservados tras su implante en animales de experimentación. Material y métodos. Arterias ilíacas de rata Spraque-Dawley fueron criopreservadas de manera automatizada, en un congelador biológico, con un rango de disminución de temperatura de 1ºC/min. Fueron almacenadas a 145ºC en vapores de N2 líquido durante 30 días y sometidas a descongelación lenta y computerizada. Los injertos singénicos, se efectuaron a nivel de la arteria ilíaca común. Se establecieron los siguientes grupos de estudio: GI: arterias criopreservadas no implantadas, GII: microinjertos frescos implantados y GIII: arterias criopreservadas e implantadas. Manteniendo como grupo control (GC), arterias ilíacas frescas. Los animales fueron sacrificados a los 14, 30 y 90 días post-injerto. Se valora la hiperplasia intimal sobre los injertos mediante morfometría, se realizan técnicas de TUNEL y respuesta macrofágica. Resultados. La permeabilidad en el momento del sacrificio fue del 100 per cent para homoinjertos fresco y 66.6 per cent para los implantes criopreservados. El propio proceso de criopreservación (GI) indujo daño en la pared arterial sobre todo a nivel endotelial mostrando áreas de denudación de diferente extensión y una buena celularidad de la capa media. La hiperplasia intimal sobre el injerto a los 14 días de implante (GII), estaba visiblemente retrasada hasta los 30 días cuando el injerto era criopreservado (GIII). Las arterias de este último grupo, mostraban un adelgazamiento general de la pared arterial y degeneración con pérdida de celularidad a nivel de la capa media del injerto. La presencia macrofágica fue similar en los dos grupos implantados, limitándose a zonas de anastomosis e hiperplasia. Los estudios de daño celular mostraron mayor número de células marcadas en el GIII a los 90 días post-implante. Conclusiones. La respuesta hiperplásica se modifica cuando el injerto ha sido previamente criopreservado, el retraso en su formación y una mayor tasa de muerte celular a largo plazo, sin alteraciones en la respuesta macrofágica, parecen ser indicativos de una clara tendencia a la degeneración del mismo a largo plazo (AU)

[Three cases of thymic hyperplasia associated with hyperthyroidism].

We encountered three cases of thymic hyperplasia associated with hyperthyroidism. Case 1 was in a 35-year-old woman; a chest CT scan showed an anterior mediastinal mass and right-sided pleural effusion, which suggested the presence of a thymoma Case 2 was in a 21-year-old man who complained of palpebral ptosis and also had myasthenia gravis (Osserman type I). Case 3 was in a 47-year-old woman; a chest CT scan showed thymic hyperplasia and mediastinal lymphadenopathy. In all cases, anti-thyroid medication was given first, because of the associations with hyperthyroidism. Moreover, in cases 1 and 2 no tumor was found, and only hyperplasia was detected in the thymus, although both patients underwent extended thymectomy. Furthermore, surgery was not effective against the hyperthyroidism (anti-thyroid medication could not be withdrawn or reduced). In cases 2 and 3, thymic hyperplasia, as seen on chest CT scans, resolved as thyroid function was normalized by anti-thyroid medication. The pretracheal lymphadenopathy seen in case 3 also resolved. Thymic hyperplasia may have been a result, not a cause, of hyperthyroidism. When we encounter patients with thymic masses and hyperthyroidism, we should give anti-thyroid medication and observe the thymus for some time before resorting to surgery.

An approach to mediastinal masses associated with hyperthyroidism.

Benign thymic hyperplasia (BTH) is a known feature of hyperthyroidism, but is infrequently appreciated by clinicians. In most cases thymic enlargement is minimal; however, it may occasionally present as an appreciable anterior mediastinal mass. While surgical resection is a common approach to such a mass, recognition of the benign nature of BTH and its regression following treatment of hyperthyroidism would prevent a major surgical procedure. We present three cases of BTH associated with hyperthyroidism and describe our approach to this syndrome.