Unclassified hemangioma-like renal cell carcinoma: a potential diagnostic pitfall

Primary intrarenal hemangioma - A series of 39 cases

Intrarenal hemangiomas lack concise clinicopathologic information, due to the predominance of single case reports and inclusion of other vascular neoplasms and hemangiomas of perirenal, hilar, and renal vein origin. Herein, in this multi-institutional study we evaluate clinicopathologic features of 39 intrarenal hemangiomas. The median age was 62 years (range = 27-94 years; 2:1 male to female ratio), with left-sided predominance (left = 21, right = 13; one case was bilateral). The median tumor size was 1.5 cm (0.2-10 cm). Two cases arose from transplanted kidneys. Most were asymptomatic (n = 30, 86 %), even though most surgical interventions (19 partial, 19 radical, 1 biopsy) were due to hemangiomas (n = 24, 62 %). Synchronous renal neoplasms were present in 9 (23 %) patients, including clear cell renal cell carcinoma (RCC) (n = 4), angiomyolipoma (n = 2), oncocytoma (n = 2), and chromophobe RCC (n = 1). Multifocal hemangiomas (n = 5) were seen in cases with end stage renal disease. Intrarenal hemangiomas were mostly anastomosing (n = 18; 46 %), followed by capillary (n = 15; 38 %), and cavernous (n = 6; 16 %) subtypes. Fibrin thrombus (n = 9; 23 %) and extramedullary hematopoiesis (n = 4; 10 %) were occasionally present, the latter being only in the anastomosing subtype. Immunohistochemistry was performed on a majority (n = 33, 84 %) of hemangiomas, with vascular markers CD31 and CD34 and lack of PAX8 were most used for diagnosis. 30 patients had follow-up (median 48 months, range 1-241 months), none showed disease progression/recurrence. This study provides comprehensive observation of the largest intrarenal hemangioma cohort, highlighting their frequent cause of surgical intervention when present, predominance of anastomosing subtype, multifocality in end stage kidney disease, and occasional concurrent ipsilateral neoplasms.

Hemangioma-Like Clear Cell Renal Cell Carcinoma Exhibiting Aggressive Behavior and High Stage: A Case Report

Clear cell renal cell carcinoma (CCRCC) displays a variety of architectural patterns, which are often intermingled. However, a predominant or purely multicystic growth with diffuse intracystic hemorrhage leading to hemangioma-like histomorphology, is extremely rare in CCRCC. In this article, we describe a CCRCC exhibiting a pure hemangioma-like architecture and aggressive behavior. The patient was a 73-year-old man with a tumor of the left kidney measuring 70 mm in the largest dimension. Histological examination of the nephrectomy specimen revealed a tumor composed entirely of blood filled spaces lined by a single layer of flattened or low cuboidal cells lacking high-grade features or voluminous clear cytoplasm. These cells showed diffuse immunohistochemical positivity for keratin AE1/AE3 and carbonic anhydrase 9 and focal positivity for PAX8, CD10, and alpha-methylacyl-CoA racemase. The tumor invaded the renal vein; no lymph nodes or extension of the tumor into the soft tissues of the hilum were detected (stage pT3a pNx). Using the Illumina TruSight Oncology 500 kit, a clinically significant c.3481dup, p.(Arg1161LysfsTer13) and c.2050del, p.(Gln684Asnfs4) mutations of the tet methylcytosine dioxygenase 2 (TET2) gene and c.296, p.(Pro99GlnfsTer60) mutation of the von Hippel-Lindau (VHL) gene were identified. The immunophenotype and molecular genetics of our tumor were consistent with CCRCC, suggesting that the unusual hemangioma-like growth pattern is most likely the result of extensive regressive changes. In contrast to all previously published reports, our study demonstrated that, despite the bland histological appearance, renal cell carcinomas with hemangioma-like features can invade the renal vein and follow an aggressive clinical course.

Renal Cell Carcinoma With Hemangioma-Like Features: Diagnostic Implications and Review of the Literature

Renal cell carcinoma (RCC) with clear cell morphology may show a prominent delicate vascularity. In this article, we report the morphologic and immunohistochemical features of a clear cell papillary RCC mimicking hemangioblastoma and a clear cell RCC mimicking hemangioma. Case 1 showed tubular and papillary growth of clear cells with distinctive areas of capillary proliferation and admixed stromal-like cells resembling a hemangioblastoma. Case 2 consisted of homogeneously delicate microvascular proliferations resembling a capillary hemangioma with scattered inconspicuous clear cells. The clear cells of Case 1 were PAX8(+), CK7(diffuse+), CA9(diffuse+, cup-shaped), and inhibin A(−). The hemangioblastoma-like areas were PAX8(+), CK7(−), CA9(diffuse+), and inhibin A(diffuse+). Case 2 showed PAX8(+), CK7(−), and CA9(diffuse+). They can be diagnostically challenging, and it is important to recognize that a pure hemangioma or hemangioblastoma of the kidneys is very rare, and that RCCs with clear cell morphology rarely exhibit hemangioma-like characteristics.