Table of Contents
Definition / general | Epidemiology | Sites | Clinical features | Radiology description | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Molecular / cytogenetics description | Electron microscopy description | Differential diagnosisCite this page: Guilmette J, Albadine R. Hybrid oncocytic / chromophobe tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/kidneytumoroncocyticchromhybrid.html. Accessed January 18th, 2021.
Definition / general
- Hybrid oncocytic / chromophobe tumor (HOCT) is a rare renal neoplasm classified as a subcategory of chromophobe renal cell carcinoma (Am J Surg Pathol 2013;37:1469)
- Displays histological features of both renal oncocytoma (RO) and chromophobe renal cell carcinoma (ChRCC) including areas composed of "hybrid" cells with overlapping cytonuclear or histochemical features (Virchows Arch 2013;462:633)
- Occurs (or arises) in three clinical settings: a sporadic tumor, associated with renal oncocytomatosis, and as a component of Birt-Hogg-Dubé syndrome (Histol Histopathol 2013;28:1257)
Epidemiology
- Typically occurs in adult males with an age range of 41 - 68 years (mean of 56) (BJU Int 2009;103:1381)
Sites
- Kidney: can develop either unilaterally (sporadic) or bilaterally (Histol Histopathol 2012;27:1407)
Clinical features
- No specific clinical symptoms reported in patients with sporadic or associated with renal oncocytosis (Histol Histopathol 2013;28:1257)
- Patients with Birt-Hogg-Dubé syndrome usually have characteristic clinical features: skin tumors such as fibrofolliculoma or trichodiscoma, pulmonary lesions including bullae and spontaneous pneumothorax (Histol Histopathol 2012;27:1407)
Radiology description
- Unilateral or bilateral solid enhancing lesions (Radiology 2003;226:33)
- May be multifocal
- Classically, lesions enhance after contrast administration and can be distinguished from cysts (Radiology 2003;226:33)
- Renal cysts may be seen (Pol J Pathol 2014;65:93)
Prognostic factors
- Good prognosis as no aggressive behavior has yet been described (Virchows Arch 2010;456:355)
- Currently, no report with follow up longer than 10 years has been published; therefore, a low malignant potential may not be eliminated (Histol Histopathol 2013;28:1257)
Case reports
- 12 year old girl with hybrid renal cell carcinoma (Pediatr Hematol Oncol 2010;27:228)
- 48 year old woman with multiple renal hybrid oncocytic tumors and Birt-Hogg-Dubé syndrome (Acta Cytol 2006;50:584)
- 52 year old woman with nonalcoholic steatohepatitis and right kidney mass (Case of the Week #379)
- Renal oncocytoma containing "chromophobe" cells (Int J Urol 1995;2:279)
Treatment
- Radical nephrectomy or nephron sparing surgery (Am J Surg Pathol 2013;37:1469, Eur Urol 2010;57:661)
- Some patients may be candidates for active surveillance, and surgery may be unnecessary (Eur Urol 2010;57:661)
Gross description
- Variable size, from 2 to 11 cm (Virchows Arch 2010;456:355)
- Well demarcated, unencapsulated mass
- Homogeneous tan to brown in color (J Urol 2011;186:2413)
- Central scar may be seen (Histol Histopathol 2013;28:1257)
- Necrosis is uncommon (Pol J Pathol 2014;65:93)
Microscopic (histologic) description
- Noninfiltrative, well circumscribed intrarenal tumor
- Solid alveolar and cystic architecture
- Dual population of eosinophilic cells: oncocytic and chromophobe
- Oncocytic cell: medium sized round cell with granular eosinophilic cytoplasm and concentric round nucleus with prominent nucleolus (Virchows Arch 2010;456:355)
- Chromophobe cell: large, polygonal "plant-like" cell with a distinct cell membrane, containing flaky eosinophilic cytoplasm often with a perinuclear halo and an irregular "raisinoid" wrinkled nucleus
- Third cell type may be seen with cytonuclear features overlapping both oncocytic and chromophobe morphology (Virchows Arch 2013;462:633)
- May have vascular invasion (Pathol Res Pract 2005;201:385)
- Mitotic rate is very low
- Rarely have necrosis (Pol J Pathol 2014;65:93)
Microscopic (histologic) images
Cytology description
- Sheets of oncocytic cells with low nuclear:cytoplasmic ratios and uniform round nuclei (Acta Cytol 2006;50:584)
- Rare cells with clear cytoplasm and slightly larger, irregular nuclei (Acta Cytol 2006;50:584)
Positive stains
- Cytokeratins: CK7 (may be focal), CK AE1 / AE3
- Parvalbumin, antimitochondrial antigen, EMA, E-cadherin (most), CD117 (Histol Histopathol 2013;28:1257, Virchows Arch 2010;456:355)
- S100A1, CD82 (Pathol Int 2015;65:126)
- Vimentin (few cases) (Pathol Res Pract 2005;201:385)
- Hale colloidal iron stains apical / luminal oncocytic cells and often intracytoplasmic in chromophobic cells (Pathol Res Pract 2005;201:385)
Negative stains
Molecular / cytogenetics description
- May be associated with BHD, autosomal dominant syndrome characterized by a genetic abnormality on chromosome 17p11.2 leading to a mutation in the FLCN gene (Pol J Pathol 2014;65:93)
- Sporadic forms may present with numerous molecular anomalies (both mono- and polysomies) of chromosomes 1, 2, 6, 9, 10, 13, 17, 21, and 22 and lack of mutations in the VHL, c-kit, PDGFRA, and FLCN genes (Virchows Arch 2010;456:355)
Electron microscopy description
- Numerous mitochondria
- Sparse microvesicles with amorphic lamellar content
- Infrequently, small intracytoplasmatic tubuli covered by microvilli may be observed (Virchows Arch 2010;456:355)
Differential diagnosis
- Eosinophilic clear cell renal cell carcinoma
- Chromophobe RCC, eosinophilic
- Other renal tumors with eosinophilic cytoplasme (SDH deficient renal cell carcinoma)
- Renal cell carcinoma unclassified
- Renal oncocytoma