Solitary fibrous tumor mimicking adrenal tumor concomitant with contralateral adrenal pheochromocytoma: A case report of surgical resection after long-term observation

Solitary fibrous tumor of the adrenal gland: a case report and review of the literature

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor, probably of fibroblastic origin, mainly in the extremities and pleura. Primary SFT of the adrenal gland is clinically more rare. Here, we report the case of a 47-year-old woman who detected a left adrenal mass on physical examination, without any symptoms, and no laboratory abnormalities. A computed tomography (CT) examination of the adrenal gland suggested a round-like soft tissue density shadow in the left adrenal area. An unenhanced scan showed uneven density of the mass, with a scattered circular-like cystic low-density shadow inside, and an enhanced scan showed obvious uneven enhancement. We considered it to be adrenal pheochromocytoma. Ultimately, the patient was treated with laparoscopic left adrenalectomy. A pathological examination suggested an adrenal SFT. We reviewed previous case reports of adrenal SFTs and summarized the clinical characteristics of adrenal SFT combined with the relevant literature. For adrenal tumors with uneven low-density shadow and uneven CT enhancement features, we should consider the differential diagnosis of adrenal SFT.

Adrenal Solitary Fibrous Tumor: A Case Report

Solitary fibrous tumor is a mesenchymal neoplasm that first appeared in the literature as a pleural lesion, but over the last decades, it has been reported in many extrathoracic sites. Primary solitary fibrous tumor in the adrenal gland is very uncommon. Its biological behavior is variable but mostly benign. We report here a case of an apparently healthy woman who, in the context of the study of limb paresthesias, was diagnosed with an adrenal incidentaloma. Laboratory tests were performed, and no hormone hyperfunction was detected. Subsequently, a right adrenalectomy was performed, and the pathological study confirmed a solitary fibrous tumor. To the best of our knowledge, this is the 19th case reported in the literature of a primary solitary fibrous tumor originating from the adrenal gland and, notably, the first documented instance in Spain.

Solitary Fibrous Tumor of the Adrenal Gland

OBJECTIVES

Solitary fibrous tumor (SFT) is a mesenchymal neoplasm that can arise at various anatomic locations. It is characterized by inv12(q13q13)-derived NAB2::STAT6 fusion, resulting in the nuclear expression of STAT6. Primary SFT of the adrenal gland is rare. We launched a multi-institutional collaboration to comprehend the overarching demographics, clinical and follow-up, macroscopic, microscopic, IHC, and FISH features of 9 patients with SFT of the adrenal gland.

METHODS

We added a series of 9 patients to the collection of adrenal SFTs where the clinicopathologic parameters, including clinical presentation, imaging, histopathology, IHC, molecular profiles, and management and follow-up data, were analyzed comprehensively. A modified 4-variable risk stratification model, including age, tumor size, and necrosis, was applied.

RESULTS

Our series consisted of 6 male and 3 female patients, ranging in age from 19 to 64 years (mean, 49.3 years). Abdominal pain (4) and fever with abdominal pain (1) were the presenting symptoms in 5 patients. In the remaining 4 patients, the tumors were detected by abdominal imaging for hypertension and diabetes. The size of the tumor ranged from 2 cm to 10.5 cm in maximum dimension. All tumors exhibited the morphology of a spindle cell SFT with a patternless architecture; 3 had a focal storiform arrangement. STAT6 positivity was observed in all tumors, and 7 were positive for CD34. Surgical resection was the primary modality of treatment. No adjuvant therapy was administered. Follow-up ranging from 7 months to 23 months was available for 7 patients. All were alive without disease recurrence or metastasis. Risk stratification placed 8 (88.9%) patients into a low-risk category and 1 into an intermediate-risk category.

CONCLUSIONS

This series is the largest of adrenal SFTs to date. These tumors of the adrenal gland are predominantly spindle cell neoplasms with indolent behavior, with a wide age distribution and a slight male preponderance. Combining our cohort with the previously published cases, the majority of tumors fall into the low-risk category for the propensity to develop metastases. Owing to the rarity and age distribution associated with these tumors, the differential diagnosis is wide and requires a systematic approach for ruling out key differential diagnoses aided by STAT6 IHC.

Solitary Fibrous Tumor of Adrenal Gland and Review of the Literature

Solitary fibrous tumor (SFT) is a rare and still controversial entity. This type of tumor first appeared in the literature as a pleural lesion, but, over the last decades, it has been reported in many extrathoracic sites. As a tumor of the adrenal gland, SFT is still rare and very uncommon, thus extensive research among the English language literature has been performed. We present here a case report of an adrenal SFT which is compared to 11 other known cases. Our case report is from a patient with SFT on the left adrenal gland, followed by mild symptoms of abdominal discomfort and hypertension. Physical examination, laboratory, and radiological tests were performed. The patient underwent surgery and the material was sent for histopathologic analysis for a definite diagnosis. Regular follow up appointments were performed over the course of two years. No recurrence of the tumor has been detected. We explain the symptoms, diagnosis, treatment, and additionally we describe the results and implications of the findings reported in the literature. Correct diagnosis is mandatory for optimal management of solitary fibrous tumor patients.

Solitary fibrous tumor of the adrenal gland – its biological behavior and report of a new case

Introduction

A solitary fibrous tumor (SFT) is an uncommon neoplasm of mesenchymal and probably fibroblastic origin, occurring mainly in the extremities, and pleura. However, a primary involvement of endocrine organs is rare and even exceptional when found in the adrenal gland. Hereby, we describe the 10th report of an adrenal SFT.

Case presentation

A 77-year old man was diagnosed with a lesion in the right adrenal gland during a urologic indicated computed tomography (CT). No symptoms and laboratory anomalies were reported indicating any endocrine activity. Follow up CT-scans showed progressive growth of the nodule for which the patient underwent laparoscopic right adrenalectomy. Histological examination showed a hypercellular spindle cell neoplasm with elongated nuclei and a low mitotic index. The vessels were arranged in a hemangiopericytoma-like pattern with a slight sclerosing appearance. Immunohistochemistry showed a positive staining of neoplastic cells for STAT6, CD-34 and Bcl-2. Translocation analysis using RT-PCR showed no NAB2-STAT6 fusion. The specimen was confirmed as a hypercellular variant of an adrenal SFT.

Discussion

SFT is a rare neoplasm when occurring in the adrenal gland. Differential diagnosis can be broad because of no defined pathognomonic morphological characteristics. However, NAB2-STAT6 gene fusions are considered a molecular hallmark of SFTs. Therefore, STAT6 immunohistochemistry is a valuable diagnostic tool in differentiating between SFT and histologic mimics. After diagnosing SFT, its biological behavior is difficult to predict. SFTs are mostly benign tumors. Nonetheless, a histological benign-appearing SFT can show malignant clinical characteristics impeding assessment of proper follow up. However, malignancy has not been previously reported in any adrenal SFT case report.

Non-adrenal tumors of the adrenal area; what are the pitfalls?

Discovery of an adrenal mass is nowadays a frequent situation. While adrenal tumors can cause a variety of symptoms, more often than not they are diagnosed incidentally on imaging exams such as CT-scan or MRI performed for another purpose. However, any retroperitoneal supra-renal mass can have an extra-adrenal origin. Indeed, operated non-adrenal masses initially but wrongly diagnosed as an adrenal disease represent about 3.5% of adrenalectomies. These differential diagnoses principally include retroperitoneal tumors that are malignant in two thirds of cases (lymphomas, sarcomas, neurogenic or germinal tumors), and more rarely vascular anomalies or congenital malformations, which are most frequently left-sided due to the wide variety of anatomical structures surrounding the left adrenal gland. Several lesions can originate from the adrenal gland or be located near the gland (paraganglioma, ganglioneuroma). Even though unilateral adrenalectomy is associated with low morbidity, ignorance of these differential diagnoses can cause ill-adapted management; overly conservative surgery in case of sarcoma is one example. Some of these lesions have characteristic clinical or imaging features (cystic lymphangioma, angiomyolipoma…). In other cases, assessment of hormonal secretion is required and additional exams (MRI, percutaneous biopsy, PET-scan with 18-Fluorodeoxyglucose) can correct an erroneous diagnosis. The above diagnostic approach allows appropriate management (with or without surgery). The purpose of this review was to highlight the main differential diagnoses of adrenal masses, to describe their characteristics, and to discuss their therapeutic management.