Cervical thymic cysts: CT appearance of two cases including a persistent thymopharyngeal duct cyst

The differential diagnosis of cervical cysts in children includes common entities such as branchial cleft cysts, thyroglossal duct cysts, and cystic hygromas. Congenital thymic cysts are uncommon and often misdiagnosed as either branchial cleft cysts or cystic hygromas. However, they may have an appearance on CT that can be characteristic. The course of the descent of embryologic thymic tissue in the neck to the mediastinum indicates the potential site of deposition of an ectopic cervical thymic cyst. In a child, a cystic lesion that has an intimate relationship to the carotid sheath is likely to be a thymic cyst. Of the approximately 100 cases of vestigial cervical thymus or thymic cysts that have been reported in children, only 5 cases of a persistent thymopharyngeal duct cyst have been described [1–5]. In two of these five, the persistent thymopharyngeal duct cyst was demonstrated by CT [1, 2]. We report one additional case of a cervical thymic cyst and one case of a persistent thymopharyngeal duct cyst both depicted by CT.     

Cervical thymic cysts

Thymic cysts are considered uncommon lesions in the differential diagnosis of pediatric neck masses. They usually present in the 1st decade after the age of 2 years, possibly because the thymus attains its greatest development before puberty. They may be found anywhere along the normal descent route of the thymus gland from the mandible to the sternal notch; 50% extend into the mediastinum. Most patients are asymptomatic, although respiratory complications may occur. A review of the operative records in our hospital over the last 10 years revealed two cases of cervical thymic cysts (CTC) in a 5- and a 9-year-old boy. Both children presented with an atraumatic, painless, enlarging mass in the left side of the neck anterior to the sternocleidomastoid muscle. Neither boy had respiratory problems or swallowing difficulties. Ultrasound and computed tomography showed a lesion consistent with a tentative diagnosis of a branchial cyst in one boy and an extensive cystic hygroma in the other. Both lesions were approached through a transverse cervical incision and, although closely adherent to the internal jugular vein, carotid artery, and vagus nerve, were resected completely. There were no postoperative complications and so far there has been no recurrence. CTCs are uncommon benign lesions that should be considered in the evaluation of neck masses in children. Preoperative diagnosis is unusual and, at this time, there is no preoperative radiologic test that can accurately identify a neck mass as a CTC. Histologic investigation of the excised specimen showing thymic tissue remnants with pathognomonic Hassall's corpuscles and cholesterol clefts in the cyst wall is the only definitive diagnosis. Evolution is benign. Intact, complete surgical excision remains the treatment of choice.     

Torsion of an ovarian cyst mimicking enteric duplication cyst on transabdominal ultrasound: two cases

We describe two girls with abdominal cysts which demonstrated the “double wall” or “muscular rim” sign. On the basis of this, the diagnosis of duplication cyst was made in each case. At surgery, both were found to have ovarian cysts, and histology revealed prominent haemorrhage within the cyst wall. To our knowledge, there has been no previous report of a false-positive “double wall sign”. Received: 24 March 1997 Accepted: 11 August 1997     

Thymic ultrasound. II. Diagnosis of aberrant cervical thymus

BACKGROUND: The aberrant cervical thymus is an uncommon entity to be considered in the differential diagnosis of neck masses in children, so a preoperative diagnosis has rarely been made. OBJECTIVE: The purpose of this study was to assess the ultrasound features of aberrant cervical thymus and determine if recognition of the previously described unique intrathymic echo pattern allows us to make a specific diagnosis. MATERIALS AND METHODS: We present four patients with an aberrant cervical thymus and one patient with a cervical thymic cyst. All five patients had ultrasound, which was evaluated with special attention to the detailed echo pattern of the mass. In two patients, the mass was surgically removed. Four patients had MRI, which was evaluated. Medical records were reviewed. RESULTS: In all cases, the mass was painless and nontender. All occurred in the expected path of the thymopharyngeal duct. In four patients, ultrasound demonstrated multiple echogenic linear structures and foci previously described as characteristic echo pattern of normal thymic tissue. In one patient, ultrasound showed a large cystic mass and echogenic solid component superiorly with a characteristic echo pattern of normal thymus. CONCLUSIONS: The ultrasound appearance of thymic tissue is unique, allowing a specific diagnosis of aberrant cervical thymus. Biopsy or other imaging is probably not indicated when it presents with typical clinical features.     

Diagnostic value of plain chest roentgenogram and CT scan findings in four cases of massive thymic hyperplasia

Massive thymic hyperplasia (MTH) is rare in the pediatric age group, especially in infants. However, because of a wide variation in size and weight of the thymus, an enlarged gland is often resected because of suspicion of a neoplasm or a cyst. Some cases of thymoma resembling pulmonary acute infection occur less frequently than MTH, but if respiratory problems are accompanied by a large thymus immediate diagnosis is often necessary to differentiate between these two conditions. Four infants (14 days to 4 months of age) with MTH were recently studied, all having an acute onset of a severe respiratory distress. The infants were referred to our center with a tentative diagnosis of thymic or other intrathoracic tumors. The following case reports illustrate our diagnostic approach to evaluate patients with symptoms suggesting MTH and the response to the “steroid test”.     

Thymus surgical pathology in children

The object of this paper is to briefly review the surgical aspects of the thymic pathology. Thymic cysts and thymic ectopy are usually asymptomatic and are one of the multiple etiologies of cervical masses. Thymic tumors are very rare and may sometimes be difficult to differentiate from simple thymic hyperplasia; being almost always separated from the normal thymic tissue by a dense capsule, they do not tend to extend rapidly. Thymectomy may be indicated in severe myasthenia.     

Pericardial cyst diagnosed by two-dimensional echocardiography and computed tomography in a newborn

Summary A one-day-old full-term female infant with massive “cardiomegaly” developed marked respiratory distress soon after birth. The two-dimensional (2D) echocardiogram demonstrated a 4×5-cm cystic mass adjacent to the left ventricular free wall. Computed tomography (CT) confirmed the presence and dimension of the cyst and CT number indicated the fluid within the cyst to be serous. A pericardial cyst was successfully removed at thoracotomy. Two-dimensional echocardiography and CT, both noninvasive procedures, are fully adequate tools in the diagnosis of pericardial cysts in the neonate, so that invasive investigations may be avoided.     

Thymic cysts of the neck

Thymic cysts of the neck are rare clinical entities. Only 45 children with cervical thymic cysts have been reported in the literature so far; 2 more cases are reported here. Both presented as cystic swellings in the left side of the neck and were pre-operatively diagnosed as a cystic hygroma and a solitary thyroid nodule. Investigations included blood counts, ultrasonograms, thyroid scans, and aspiration cytology. Both lesions could be easily excised by the cervical route. The final diagnosis was made only after histopathological examination. The relevant literature on the aetiology, pathology, clinical features, and treatment is reviewed. Offprint requests to: K. Radhakrishna     

Thymic cyst appearing after treatment of mediastinal non-Hodgkin lymphoma

We report the first case of a thymic cyst appearing in the course of treatment for non-Hodgkin lymphoma of the anterior mediastinum. The patient was a 9-year-old child in whom an abnormal contour of the left cardiac border persisted after chemotherapy, suggesting residual disease. The mass was found at thoracotomy to be a benign thymic cyst. The lesion was not present 2 years previously, and most likely represented cystic degeneration of the thymus, secondary to lymphomatous involvement. CT scan was not helpful in distinguishing the cystic lesion from residual lymphoma.     

Inspiratory stridor and dysphagia in two newborn infants caused by ectopic thymus tissue

We report two cases of ectopic cervical thymus, a solid thymic lesion, and a thymus cyst causing inspiratory stridor and mild dysphagia in the neonatal period. Because of the rarity of thymic dystopia, the two masses were initially misdiagnosed as more common entities, namely, lymph node enlargement and lymphangioma, respectively. The correct diagnosis was made only after surgical excision and histopathological examination. This case report is completed by a short review of embryogenic development, diagnostic procedures with differential diagnoses, and therapeutic outcome of ectopic thymus.     

Thymic enlargement in childhood

Thymic masses constitute one of the least common mediastinal masses in childhood. While producing symptoms of airway compromise, they also raise the suspicion of malignancy when detected. Radiological, operative and pathological findings of patients that have been operated for thymic masses in our institution is presented in this paper. Nine patients were operated in our institution during a 12-year-period between 1985-1997 for thymic masses. Ages of the patients ranged from four months to 13 years. With the exception of one, who was diagnosed with a routine chest x-ray, all the patients had respiratory complaints. All the patients had been evaluated with computed tomography preoperatively. In total, seven sternotomies and four thoracotomies were performed to reach the anterior mediastinum. The distribution of masses was as follows two malignant thymomas, three thymic hyperplasia, one lymphocyte-rich thymoma, one epithelial thymoma, one cystic thymoma and one lymphoblastic lymphoma. Although rare, thymic enlargement may be a cause of intractable respiratory complaints in childhood. Because of the high incidence of primary malignancy of the mediastinal neoplasms in childhood, thymic enlargement requires accurate pathological diagnosis and treatment. Median sternotomy with intensive anesthetical care allows proper tumoral exposure.     

Ectopic thymic hyperplasia in a patient treated for Burkitt lymphoma

Thymic hyperplasia results from thymic regrowth after atrophy during stressful conditions such as burns, surgery, infection, and chemotherapy. Although thymic lesions are relatively common causes of anterior mediastinal masses, they also can develop in other mediastinal compartments on rare occasions. It is well known that thymic tissue can develop in ectopic intrathoracic lesions. Few cases of ectopic thymus associated with disturbance during thymus embryogenesis have been reported as incidental findings. We report the case of a 4-year-old boy with true thymic hyperplasia from an ectopic thymus after successful treatment for Burkitt lymphoma. This is a rare finding in the differential diagnosis of a middle mediastinal mass in a child following chemotherapy for lymphoma. The diagnosis of thymic hyperplasia from an ectopic thymus can be confirmed only histologically.     

Ectopic cervical thymic tissue: can imaging obviate biopsy and surgical removal?

Thymic tissue rests can be found all along the route of thymic descent from the neck into the anterior mediastinum and are frequently misinterpreted as pathological masses, which leads to biopsy or surgical removal. We present a case of ectopic thymic tissue in the neck and review the imaging characteristics of our patient and those found in the literature to determine if biopsy for this normal variation can be avoided. US findings of ectopic tissue reveal the exact tissue characteristics of normal thymus. The ectopic thymus may have an angulated configuration and mold over adjacent structures rather than displacing or invading them. If further verification is needed, T1-weighted MR images show homogeneous isointense or slightly hyperintense tissue compared with muscle and T2-weighted images show hyperintensity. The mass has the same structure as the normal thymus. We believe, on the basis of these findings, that one can confidently avoid the need for biopsy to prove that the discovered mass is ectopic thymus tissue.     

Cavitation of anterior mediastinal masses in children with histiocytosis-X

Four children with histiocytosis-X had large solid mediastinal masses at diagnosis. Follow-up studies in three showed large air cysts occupying the sites of the original masses; the fourth patient had small air cysts at the periphery of the mass. All patients survived. One patient was explored and the large air cysts were in the mediastinum with adherence to the adjacent lung. Lesser pulmonary involvement was noted in the lungs of three of the four patients. Cavitation within mediastinal masses in histiocytosis-X appears to reflect two processes. The first is necrosis within the masses themselves. The second is involvement of adjacent lung with adherence of lung and pleura to the mediastinum allowing air to fill the mediastinal cavities. Presented at the Society for Pediatric Radiology Meeting, Las Vegas, Nevada, March 1984     

A pediatric case of life-threatening airway obstruction caused by a cervicomediastinal thymic cyst

Most patients with thymic cysts complain of a slowly enlarging, asymptomatic cervical mass. Only 6–10% suffer dysphagia, dyspnoea, stridor, cervical pain or vocal paralysis. In some rare cases sudden onset of severe dyspnoea or asphyxia is the first symptom, especially in neonates and small infants. We report a unique case of a 20-month-old child, who required emergency tracheal intubation due to asphyxia. Cervicomediastinal thymic cyst might need to be included in causes of life-threatening airway obstruction in young children.     

Mesothelial cyst of the liver in a neonate

Mesothelial cysts are very rare congenital cystic lesions that are derived from coelomic remnants. We report a neonate with a mesothelial cyst of hepatic origin. On routine antenatal ultrasound study, an intra-abdominal mass was seen. After birth, the cystic lesion’s size increased to 8 cm and became symptomatic. Surgical resection was performed. Preoperative diagnostic imaging studies, including CT and MRI, did not identify the etiology, but the cyst appeared to be of hepatic origin. Intra-operatively, the cystic lesion was confirmed to have originated from the liver. Based on immunohistological analysis, the final diagnosis was mesothelial cyst of the liver.     

Isolated fallopian tube torsion: sonographic and CT features

Background Isolated fallopian tube torsion (IFTT) rarely occurs in pediatric patients and is difficult to diagnose preoperatively. Objective To determine the common sonographic and CT findings in girls with IFTT. Materials and methods We retrospectively reviewed the hospital charts and imaging studies of the eight girls diagnosed with and treated for IFTT at Columbus Children’s Hospital between January 1995 and June 2006 whose final diagnosis was IFTT. Results The mean age was 13 years with a range of 12 to 15 years. Two girls were premenarcheal. The most common presenting symptom was acute pelvic pain (n = 5). All patients were imaged. Six girls were imaged first with US, and the most common finding was a complex cystic pelvic mass in the midline (n = 5) and normal uterus and ovaries. Three of the eight girls had imaging with CT. In two girls, the torsed tube could be identified. In 63% of the girls, the uterus was deviated toward the side of torsion. The correct preoperative diagnosis was made in only one girl. None of the torsed fallopian tubes was salvaged at surgery. Pathological findings included ipsilateral adnexal cysts associated with the torsed tube (n = 7). Conclusion IFTT should be considered in the differential diagnosis for perimenarcheal girls who present with acute pelvic pain and who demonstrate a cystic mass in a midline position (either in the cul-de-sac or superior to the uterus) associated with a normal ipsilateral ovary.     

Disappearing fetal lung masses: importance of postnatal imaging studies

Background. The “disappearance” of congenital masses of the lung on prenatal sonograms has been described, but the importance of postnatal imaging studies in these children is unknown. Objective. The objective of this work was to study the utility of radiographs and CT scans in asymptomatic infants with congenital masses of the lung that partially or completely resolve on prenatal sonograms performed late in gestation. Materials and methods. The prenatal sonograms, postnatal imaging studies, surgical findings, and pathologic diagnoses of seven children with an echogenic mass of the lung that improved or disappeared on prenatal sonograms were reviewed. Results. All masses were type II congenital cystic adenomatoid malformation, with features of intralobar sequestration also being found in four. An unsuspected extralobar sequestration adjacent to a left lower lobe mass was found at surgery in one patient. All masses were hyperechoic compared with normal lung on sonograms prior to 32 weeks of gestation, with cysts being seen in four. On scans after 32 weeks, four of the masses had resolved completely and three showed subtle increased echogenicity compared with normal lung. Cysts completely resolved in two of four cases. Postnatal radiographs showed subtle abnormalities in four infants, a hyperlucent lobe in one, a soft tissue mass with adjacent hyperlucency in one, and normal findings in one. CT scans were abnormal in all cases, with air-filled cysts and soft tissue in six and a hyperinflated lobe in one. Conclusion. Children with “disappearing” fetal lung masses have persistent abnormalities after birth that are often subtle on radiographs but are well demonstrated with CT. Received: 16 April 1996 Accepted: 26 September 1996     

Efficacy of OK-432 local injection for the treatment of a neonatal branchial cleft cyst: a case report

We herein present a case of a neonatal cervical cyst, which was diagnosed prenatally, and markedly decreased in size and disappeared after a local injection therapy of OK-432. A 0-day-old boy had an abnormal prenatal ultrasonography scan suggestive of rt. cervical cyst, measuring about 25 mm in diameter at 29 weeks’ gestation. At birth, an elastic soft mass, measuring about 30 mm in diameter, was found on the right side of his neck. Computed tomography (CT) scans showed a giant cyst, which extended from the upper level of epipharynx to the upper mediastinum, and the contents were air and fluid. At 20 days of age, ultrasonography (US)-guided needle aspiration was performed. The aspirated fluid contained no epithelial cells, but many lymphocytes and neutrophils based on a cytological analysis. After the local injection of OK-432 had been performed four times, the right neck cyst had almost completely disappeared on US scans. During the local injection therapy, we analyzed the other sample of the second aspiration fluid of the neck cyst. Several clusters of epithelial cells, columnar epithelium, squamous cells, and ciliated epithelium were thus cytologically observed. Therefore, a final diagnosis of a branchial cleft cyst was made. The local injection of OK-432 was thus found to be an effective treatment for branchial cleft cysts.     

Giant cystic abdominal masses in children

In this pictorial essay the common and uncommon causes of large cystic and cyst-like abdominal masses in children are reviewed. We discuss and illustrate the following: mesenchymal hamartoma, choledochal cyst, hydrops of the gallbladder, congenital splenic cyst, pancreatic pseudocyst, pancreatic cystadenoma, hydronephrosis, multicystic dysplastic kidney, multilocular cystic nephroma, adrenal hemorrhage, mesenteric and omental cysts, gastrointestinal duplication cyst, meconium pseudocyst, ovarian cysts and cystic neoplasms, hematocolpos, urachal cysts, appendiceal abscess, abdominal and sacrococcygeal teratoma, and CSF pseudocyst. We also describe imaging features and clues to the diagnosis.