Adrenal Pseudocysts: Evidence of Their Posthemorrhagic Nature

Longitudinal CT and MRI Characteristics of Unilocular Thymic Cysts

Background Isoattenuating and hyperattenuating thymic cysts at CT are often misinterpreted as lymphadenopathy or thymic epithelial neoplasms. Purpose To evaluate the longitudinal change in thymic cyst appearance at CT and MRI. Materials and Methods All chest MRI studies showing thymic cysts between July 2008 and December 2019, identified from a retrospective search of a quality assurance database, were included in this study if initial CT depicted a thymic lesion, the patient was referred for follow-up MRI for characterization, and the baseline (ie, index) MRI indicated a cystic lesion. Follow-up CT scans and/or MRI scans were identified through July 2020. Thymic cyst characteristics, such as size, location, and morphologic features, as well as CT and MRI characteristics, were recorded. Change in size, attenuation, and T1-weighted MRI signal was assessed longitudinally. Descriptive statistics of longitudinal change were tabulated. Results A total of 244 chest MRI studies in 140 patients with 142 unique cysts and 392 CT examinations (636 total examinations and 645 thymic cysts-nine examinations with two cysts each) were evaluated. The median follow-up duration was 2.2 years. Thirty-three patients with 34 unique cysts (34 of 142 cysts [24%]) underwent imaging follow-up for more than 5 years. Thymic cysts followed up for more than 5 years were most commonly saccular (189 of 274 cysts [69% axially]) and retrosternal (14 of 34 cysts [41%]). Craniocaudal dimension was larger than transverse and anteroposterior dimensions in 223 of 274 cysts (81%). Mean thymic cyst attenuation was 25 HU (range, 15-100 HU). Five of 31 cysts (16%) exhibited wall calcification. The median cyst wall thickness was 2.0 mm (range, 0.9-3.0 mm). Most thymic cysts changed in volume (31 of 34 cysts [91%]), CT attenuation (15 of 35 cysts [43%]), and T1-weighted MRI signal (12 of 18 cysts [67%]) over time. None developed mural irregularity, nodularity, or septations. Conclusion Unilocular thymic cysts, defined at index MRI, never developed irregular wall thickening, mural nodularity, or septations that would raise concern for malignant transformation. However, these cysts showed mural calcification and change in size, CT attenuation, and MRI signal over more than 5 years of follow-up. © RSNA, 2021 Online supplemental material is available for this article.

Giant adrenal pseudocyst: A rare diagnosis

We present a rare case of giant adrenal pseudocyst as a cause of right upper quadrant (RUQ) pain and highlight the typical multimodality imaging features. The case demonstrates the imaging features associated with giant adrenal pseudocysts to aid accurate and timely diagnosis. Despite the rarity of these lesions they are important to consider as benign lesions can closely mimic malignant ones. Unenhanced and contrast-enhanced CT is the imaging of choice for adrenal cysts. However, MRI can provide more exquisite assessment of cystic, solid and enhancing components. Pseudocysts can be purely cystic, mixed or solid. Classically, adrenal pseudocysts are described as cystic lesions (of homogenous water density) with a fibrous wall and thin internal septations. Mural/septal calcification is commonly demonstrated due to haemorrhage, this is discernible from central/amorphous calcification seen in malignant disease. As in this case, pseudocysts can contain solid components or layering secondary to haemorrhage. The key to differentiating organised haematoma from tumour is the lack of enhancement. If serial imaging is undertaken in these patients rapid changes in the solid components may be seen reflecting resolving haematoma. Adrenal pseudocysts are rare and have a wide differential. Cystic adrenal lesions warrant multimodality assessment as their imaging features aid diagnosis and differentiation from malignant disease. We suggest that MRI plays a complimentary role to CT. CT is superior at demonstrating mural/septal calcification but MRI aids in determining cystic components and differentiating haemorrhage from tumour.

Non-neoplastic adrenal pseudocysts: A clinicopathologic study of 44 cases with potential insights into pathogenesis

BACKGROUND

Literature on non-neoplastic adrenal pseudocysts (NNAPC) remains limited and to date no large series have been reported. The pathogenesis of these lesions remains poorly defined, however a vascular origin is most often suggested in the literature. We aimed to evaluate the clinicopathological features and the spectrum of vascular changes within NNAPC, in order to better understand the mechanisms and circumstances of their pathogenesis.

METHODS AND RESULTS

We reviewed 44 cases of surgically resected NNAPC. There were 30 females and 14 males ranging from 23 to 82 years (median, 53 years). On the basis of histopathologic and immunohistochemical analysis of the vascular changes the following types were defined: pseudocysts with lymphatic-related changes (type 1, n = 16), pseudocysts with large vein-related changes (type 2, n = 15) and pseudocysts with blood vessel microvasculature-related changes (type 3, n = 13). The median patient age of the latter group was higher than that of type 1 and 2 (64 years versus 51 and 50 years, respectively; p = 0.0002). Type 3 pseudocysts were more frequently associated with a history of systemic vascular and vascular-related disorders than type 1 and type 2 pseudocysts (92% versus 33% and 64%, respectively; p = 0.008). Type 1 pseudocysts were more frequently connected with a history of previous intra-abdominal surgical procedures than type 2 and 3 pseudocysts (60% versus 7% and 25%, respectively; p = 0.0079).

CONCLUSIONS

NNAPC are clinically heterogenous and can arise on a background of various vascular changes. They may represent end-stage processes related to lymphangiomatous lesions, changes in adrenal venous structures or microvasculature.

Composite paraganglioma and ganglioneuroma in the retroperitoneum: a case report

Reports of a composite paraganglioma (PG) and ganglioneuroma (GN) in the retroperitoneum are rare. In the present case, dynamic computed tomographic (CT) findings showed a 30 × 22 × 20 mm tumor that was located in the retroperitoneum and which was dissociated from pancreatic tissue and the left adrenal gland. The markedly reddish tumor showed a clear margin and central multicystic changes on the cut surface. The tumor was composed of two major components, the PG and the GN. The paraganglionic cells in the PG component, which were arranged in a nested pattern, occupied the main and central part of the tumor. Both ganglionic cells and Schwann cells in the GN were located in a unorganized pattern in the periphery. The paraganglionic cells exhibited a Zellballen pattern, which consisted of an association of edematous vascular-rich stroma and focal hemorrhage, resulting in multicystic changes. These centrally located tumor cells were pleomorphic in part and did not have mitotic figures. In the periphery, Schwann cells, which were arranged in an obscure and fascicular pattern that was intermingled with large ganglionic cells, were located adjacent to the PG component with a mostly sharp margin. With higher magnification, the border was not as sharp, as revealed especially with chromogranin-A immunostain, in which both the PG and GN components were focally intermingled with each other. The histogenesis of the composite PG and GN was thought to be extraadrenal neural crest cells in the retroperitoneum because the tumor was not located in the adrenal gland or the Zuckerkandl organ, according to the CT findings. The immunohistochemical findings of this rare case of a composite PG and GN in the retroperitoneum are reported with a focus on the peculiar arrangement of these two components.

Extra-adrenal composite paraganglioma with ganglioneuroma component presenting as a pancreatic mass

Paragangliomas may have composite forms in which they combine features of a typical paraganglioma with those of a neural component consisting of either neuroblastoma, ganglioneuroblastoma, or ganglioneuroma. These variants are rare and generally located in the adrenal. Herein, we describe a retroperitoneal, extra-adrenal composite paraganglioma-ganglioneuroma of a 57-year-old woman. Radiological evaluation revealed a nodular mass with apparent pancreatic location, with findings suggestive of an endocrine tumor, yielding the diagnosis of a pancreatic endocrine tumor. At histology the neoplasm, strictly adhering to the external surface of the pancreatic gland but well demarcated, displayed a main central region with typical paraganglioma features and cells arranged in cords and in a nesting "zellballen" pattern, positive for neuroendocrine markers, and a distinct peripheral area consisting of dense bundles of wavy spindled Schwann cells, with scattered ganglionic cells.

Papillary Endothelial Hyperplasia of the Adrenal Gland: Report of a Case and Review of the Literature

Papillary endothelial hyperplasia (PEH) is a benign vascular proliferative process most frequently seen in the skin and integument, but may involve any of the visceral organs. It is a rare entity, with less than 30 cases of visceral PEH described in the literature. Adrenal papillary endothelial hyperplasia is an exceedingly rare process and is the basis of this review. A 66-year-old female was referred for evaluation of an asymptomatic 6 cm right adrenal mass. Computed tomography indicated that the lesion was solid and hypervascular. After appropriate workup, the patient underwent laparoscopic adrenalectomy. The pathologic analysis was consistent with adrenal PEH. The patient recovered without incident and is doing well at 1 year follow-up. A review of the world's literature on papillary endothelial hyperplasia (PEH), and in particular adrenal PEH, yields five previous reports of this entity, and no comprehensive review. A compilation of the now six patients with adrenal PEH reveals several common features: five of six patients were female and mean age was 64 years. The disease radiologically mimics adrenal cortical carcinoma mandating a surgical oncological technique. Pathologic differentiation from angiosarcoma can be a difficult task requiring evaluation by an experienced pathologist.

Vascular adrenal cysts: a brief review of the literature

Adrenal cysts are rare and form a heterogeneous group of lesions that includes (a) parasitic cysts, (b) epithelial cysts, (c) pseudocysts, and (d) endothelial cysts. There is evidence (immunohistochemical and ultrastructural) that both pseudocysts and endothelial cysts are variants of vascular cysts. Adrenal vascular cysts account for 84% of adrenal cysts. They are more common in women and present clinically with abdominal pain or are incidental findings. Their imaging features are not specific. Grossly, both types of adrenal vascular cysts are encapsulated. Pseudocysts are unilocular, thick-walled, and devoid of endothelial lining, whereas endothelial cysts are thin-walled, multilocular, and lined by endothelium. Adrenal vascular cysts probably originate from a preexisting vascular hamartoma. The treatment of choice is surgical excision. The prognosis is excellent.

Composite paraganglioma-ganglioneuroma of the urinary bladder

Presented herein is the case of a 73-year-old man, complaining of dysuria, who had a composite paraganglioma-ganglioneuroma of the urinary bladder (CPGUB). At cystoscopy a submucosal tumor was found in the urinary bladder and resected after transurethral biopsy. The levels of serum catecholamine and 24 h urinary excretion of catecholamine and vanillylmandelic acid were elevated. Grossly, the resected tumor, measuring 4 x 3 x 2.5 cm, had a brownish cut surface with no necrosis and hemorrhage. Histologically, the tumor had alternating cellular and fibrous areas. The cellular areas consisted of polygonal cells, arranged in well-defined nests (Zellballen) and positive for Grimelius staining, with abundant amphophilic to acidophilic cytoplasm, occasionally containing eosinophilic hyaline globules and brown pigments. Although the nuclei of several polygonal cells were bizarre, mitoses and vascular invasion were not found. Fibrous areas consisted of spindle cells, resembling Schwann cell, admixed with ganglionic cells. To the authors' knowledge, only four cases of CPGUB have been reported in the English-language literature. Detailed reported cases and the present case showed no malignant features, such as extra-bladder infiltration and metastasis, and no recurrence in the short length of follow up. Accumulation of long-term follow-up cases may provide valuable prognostic information on this composite tumor.

Mature cystic teratoma involving adrenal gland

A mature cystic teratoma presented as an adrenal mass in a 57-yr-old woman. The tumor was found to be predominantly paraadrenal but focally interrupted the adrenal cortex so that an intraadrenal origin could not be ruled out. Similar lesions have been reported extremely rarely and should be considered in the differential diagnosis of hormonally silent adrenal tumors. The findings of rimlike calcification and fatty density on computed tomography may be helpful diagnostically.