Adrenal Adenoma-Hemangioma Collision Tumor: description of two cases
Adrenal Adenoma-Hemangioma Collision Tumor
Patient 1: a 63-year-old male presented to our institute in order to perform the 1st routine CT exam, 6 months after an enucleoresection of a small left kidney clear cell carcinoma. Preoperative exams like ultrasound, CT and MRI, as well as the enucleoresection itself, were performed in another institute and they were not available at the time of our 1st CT, which showed regular aspects of a kidney enucleoresection and a left adrenal oval lesion with smooth margins diagnosed in the other institute as a simple adrenal adenoma. In our CT exam the adrenal lesion features were not completely suggestive of a simple adenoma: we suspected the presence of an adrenal adenoma-hemangioma collision tumor. Patient 2: a 76-year-old woman presented to our institution to perform a preoperative CT urography scan for a papillar bladder carcinoma to be removed and previously identified by ultrasound and diagnostic cystoscopy. The patient in the past underwent mastectomy for a breast cancer, pulmonary superior left lobectomy for an adenocarcinoma in 2013 and a lung segmentectomy for a MALT-oma in 2016. At the basal CT examination, in addition to the bladder lesion, an oval 20mm nodule with regular margins was found in the left adrenal gland characterized by two components, a more peripheral one with a density lower than 10UH compatible with adenomatous tissue and a more central one with density of 28UH: we suspected the presence of an adrenal adenoma-hemangioma collision tumor.
Patient 1:in the CT unenhanced sequence the lesion showed two different densities, one more peripheral with the classic adenoma features (density < 10HU) and another central one with a round morphology and with a density of 25HU (Fig 1A). Arterial and venous phases showed faint inhomogeneities of the central component with the suspicion of little spots of globular enhancement at the interface between the two components (Fig 1B-1C). Delayed phase at 15minutes after contrast bolus injection showed a late enhancement of this central part of the lesion (Fig 1D). Therefore, we performed a MRI exam in order to obtain a better characterization of this adrenal lesion: the peripheral component showed a classic adenomatous aspect with a signal loss in the out of phase T1w images, while the central one showed inhomogeneous hyperintensity in T2w and T2w fat sat images better seen at the interface (Fig 2A-2B), no signal restriction with high b value on DWI and an ADC value of 1299x10-6mm2/s (Fig 2C-2D), isointensity compared with muscle and spleen in both in phase and out of phase T1w images (Fig 2E-2F) as well as in the unenhanced T1w 3D VIBE. The dynamic subsequent sequences showed a progressive centripetal globular enhancement till the complete persistent hyperintensity in the delayed phase at 15 minutes after bolus administration (Fig 3A-3B-3C-3D-3E). Moreover, we retrospectively re-evaluated the preoperative MRI performed 6 months before our follow up CT exam and the adrenal lesion had the same features. On the basis of the overall benign features of this lesion, we postulated that the more probable diagnosis was an adrenal adenoma-hemangioma collision tumor and considering the wish expressed by the patient not to undergo another surgery or other invasive exams, a 6 months MRI follow up strategy has been established: after 24 months the lesion was unchanged as regards morphological and dynamic features (Fig. 4A-4B). Patient 2: At the basal CT examination, in addition to the bladder lesion, an oval 20mm nodule with regular margins was found in the left adrenal gland characterized by two components, a more peripheral one with a density lower than 10UH compatible with adenomatous tissue and a more central one with density of 28UH (Fig 5A). In the dynamic phases the central component had a globular enhancement, visible in the early arterial phase as small peripheral spots and then presenting a centripetal and progressive vascularization up to the persistent complete hyperdensity at about 15 minutes from the administration of the contrast medium (Fig 5B-5C-5D). On ultrasound examination, this adrenal lesion appears to be substantially hypoechoic with a central component that is slightly hyperechoic, corresponding to the non-adenomatous part (Fig 6). Retrospectively analyzing some unenhanced thoracic follow up CT performed in previous years after lobectomy, we realized that this feature of the lesion was already visible and substantially unchanged even if co
Adrenal collisions tumors (ACTs) are defined as the coexistence of two adjacent, but histologically distinct tumors of the adrenal gland without a substantial histologic admixture at the interface. By contrast, composite tumors are neoplasms with an intimate admixture of two different cell types. The pathogenesis of ACTs has been debated, as the limited number of cases reported precludes detailed analysis of their etiology. Two theories have been postulated to describe their pathogenesis. The first and the simplest explanation is that two different primary tumors merely occur together by chance. A second hypothesis supposes that a single carcinogenic stimulus alters a particular region in the adrenal gland, allowing two separate tumors to occur in contiguity, or the presence of one tumor may alter the local environment, providing a fertile ground for the development of a second tumor.These tumors are usually incidentally detected during work-up for some other disease. In the adrenals, detection of incidentalomas has increased with the extensive use of cross-sectional imaging and most of these are adenomas or metastases. Preoperative diagnosis of individual components of ACTs is again another challenge. Each component of the collision tumor presents its own features. Adrenal adenomas most important findings are density inferior to 10UH in unenhanced CT, absolute wash out more than 60%, and signal drop in out of phase T1weighted sequences . Hemangiomas show inhomogeneous density when large at unenhanced CT due to cystic component, hemorrhage or calcifications. They appear hypointense in T1w and hyperintense in T2w sequences while on both CT and MR, after the administration of intravenous contrast, hemangiomas typically demonstrate peripheral nodular enhancement with or without centripetal fill-in on delayed images. It has been suggested that centripetal enhancement on dynamic MRI has not been reported in other adrenal tumors, and if present, should enable differentiation of hemangiomas from other adrenal tumors.
Adrenal collision tumors are rare clinical entities referring to separate coexisting adjacent tumors with sharp demarcation between the two and without a substantial histologic admixture at the interface. Diagnostic imaging is very important in differentiating benign from malignant components of the collision tumor and the subsequent management. Adenoma-Hemangioma collision tumor is an exceedingly rare entity that must be considered in the differential diagnosis of an adrenal mass, as described in our report.