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 August 3rd, 2020.
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
Contributed by Chin-Lee Wu, Ph.D., Harvard School of Medicine
Dual population of eosinophilic cells
Contributed by Roula Albadine, M.D. and Julie Guilmette, M.D.
Flaky eosinophilic cytoplasm
Oncocytic cells with granular eosinophilic cytoplasm, concentric round nucleus and prominent nucleoli
Hale colloidal iron
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
