Kidney - prev exam q Flashcards
oncocytoma
histo variants
- Classic
- tubulocystic
- mixed
Describe classic histo pattern of oncycytoma
- Organoid pattern with well-defined nests of tumor cells
- Edematous, myxoid, or hyalinized stroma
- Confluent nests of tumor cells can be seen at the periphery of the lesion; nests of tumor cells should be outlined by interlacing framework of thin fibrous septa
Describe
- Tubulocytsic oncocytoma
- Mixed oncocytoma
Tubulocystic
- Variably sized tubular and cystic structures
- Spaces often contain eosinophilic secretion
Mixed pattern
- Composed of both organoid and tubular architecture
Cytological features oncocytoma
- Tumor cells have finely granular eosinophilic cytoplasm
- Round nuclei with smooth, regular contour and evenly distributed chromatin
- Presence of nucleoli is variable; may be absent or prominent
- Absence of mitotic figures
- Focally cells with hyperchromatic, smudged nuclei may be seen
Other unusual features
- Focal extension into perirenal fat, which has no adverse effect on the prognosis
- Focal cytoplasmic clearing, especially in scarred area
Features that are inconsistent with a diagnosis of Oncocytoma
- Gross extension into perirenal adipose tissue or gross vascular invasion
- Papillary architecture
- Sarcomatous or spindle cell areas
- Atypical mitotic figures
- Positive for colloidal iron stain
IPX oncocytoma
- Cytokeratin 7 stains single cells or clusters of cells
- Vimentin: negative
- S100A1: positive
- Hale’s colloidal iron stain: negative or only stains luminal cytoplasm
- E-cadherin and kidney specific cadherin: positive
- Claudin 8: positive cytoplasmic staining
ONCOCYTOMA PEARLS (4)
- Believed to arise from the intercalated cells of collecting ducts
- Oncocytomas are benign tumors; previous reports of malignant oncocytomas are almost certain RCC misdiagnosed as oncocytomas
- Most common histologic features include well-defined nests of eosinophilic tumor cells separated by fine, delicate fibrous bands and a central fibrous scar
- Hybrid oncocytic tumors with features of both oncocytoma and chromophobe RCC (HOCT) can be seen in patients with Birt-Hogg-Dube syndrome
DDX oncocytoma
- Eosinophilic variant of clear cell RCC
- Chromophobe RCC, eosinophilic variant
- Renal oncocytosis
RCC WITH EOSINOPHILIC CYTOPLASM
- Eosinophilic cytoplasm can be seen in high-grade clear cell RCC, but presence of clear cells or papillary structures precludes the diagnosis of oncocytoma
- Nuclear grade is usually high and mitosis readily identifiable
- Cytokeratin 7 negative, but vimentin positive
- E-cadherin: negative
CHROMOPHOBE RCC, EOSINOPHILIC VARIANT
- Sheetlike compact growth pattern
- “Raisinoid” nuclei and perinuclear halos
- Cytokeratin 7 diffusely positive; Hale’s colloidal iron positive
- E-cadherin: positive
- S100A1: negative
- Claudin 8: positive membranous staining
RENAL ONCOCYTOSIS
- Renal parenchyma diffusely involved by numerous oncocytic nodules and oncocytic changes: infiltrative growth of oncocytic cells, cortical cysts with oncocytic features, oncocytic changes in non-neoplastic tubules
- Unilateral or bilateral
- May occur in a sporadic form or associated (1/2) with chronic renal failure/long-term hemodialysis
Clinical Angiomyolipoma
1/5 are assoc with tuberous sclerosis
Sporatic cases are single, unilateral
TS cases are multpile, bilateral
Sharply demarcated leson, unencapsulated
Varigated cuts surface: vascular and adipose tissue and grey white solid areas corresponding to the smooth muscle component
histopathology of AML
- Triphasic tumor consisting of smooth muscle, mature adipose tissue, and thick-walled hyalinized blood vessels in varying proportion
- One component may predominate
- Atypical features may occasionally be seen, including nuclear pleomorphism and mitosis
- Smooth muscle areas may show epithelioid differentiation with cells having abundant eosinophilic cytoplasm and large nuclei with prominent nucleoli
IPX AML
- Melanocytic markers: positive
- Smooth muscle markers: positive in smooth muscle component
- Epithelial markers: negative
DDX AML
Malignant Spindle Cell Tumors, Including Leiomyosarcoma
- Lack triphasic appearance
- Poorly circumscribed tumors with infiltrative borders
- Unequivocal high-grade, malignant cytologic features
- Negative for melanocytic markers
Pearls AML
- Tumor occasionally seen in the renal vein or in regional lymph nodes, but this is not a sign of malignant transformation
- Need to sample these tumors extensively to rule out the presence of coexisting renal cell carcinoma
- Must recognize that fatty tissue is part of lesion and not interpret it as an invasion into perirenal adipose tissue
(4) types of amyloidosis affecting the kidney are:
AL amyloidosismost frequently lambda light chain type over kappa; heavy chain type;
AA amyloidosis, due to accumulation of serum amyloid A protein and associated with chronic inflammatory processes; transthyretin, although rarely affecting kidneys;
α-fibrinogen, the most frequent genetic form affecting the kidney;
β2 microglobulin, associated with dialysis; and leukocyte chemotactic factor 2.
Description amylodosis kidney
Deposition of amorphous, weakly eosinophilic acellular material in
- glomeruli,
- tubular basement membranes,
- interstitium
- vessels
Vessel features in kidney amyloid
Arteriolar intima contains nodules of pale material; arterioles and interlobular arteries are the most commonly involved
glomerular features amyloid kidney
tubule features, amyloid kidney
Glomeruli show progressively enlarged mesangium with nodules in more advanced stages, and irregular thickening of the glomerular basement membranes; pseudospikes pushing away the podocytes and made of amyloid fibrils can be appreciated on (H&E stain)
Tubules with basement membrane involvement may show irregular thickening of the basement membranes without atrophy
amyloid (in the bladder)
renal dysplasia
Renal dysplasia: abnormal metanephric differentiation, has variable presentations that cover a spectrum of conditions, including hypoplasia, multicystic dysplasia, and aplasia
“Renal dysplasia. Markedly disorganized kidney parenchyma with dysplastic ducts lined with columnar epithelium and surrounded by collars of spindle cells. Island of cartilage and cystic spaces lined by flattened epithelium. Few glomeruli are seen.”
Multicystic dysplastic kidney (MCDK) is a variant of renal dysplasia
- characterized by the presence of multiple, noncommunicating cysts of varying size separated by dysplastic parenchyma
- absence of a normal pelvocaliceal system
- associated with ureteral or ureteropelvic atresia
- affected kidney is nonfunctional.
- most common cause of an abdominal mass in the newborn period and is the most common cystic malformation of the kidney in infancy.
- Bilateral disease results in oligohydramnios (Potter syndrome), and neonatal death from pulmonary hypoplasia
DDX Cystic diseases of the kidney in paediatric population
- Renal dysplasia (esp Multicystic renal dysplasia)
- Infantile Polycystic Kidney Disease (Autosomal Recessive)
- Medullary Cystic Disease (Autosomal Dominant)
- Medullary sponge kidney
Infantile PCK
- Often results in stillbirth or early neonatal death
- Cysts are in the cortex and medulla and do not congregate at the papillary tips
- Cartilaginous metaplasia or other dysplastic elements never seen
Medulary cystic disease (autosomal dominant)
- Patients present with renal failure in first or second decade
- Cysts are located at the corticomedullary junction
Medullary sponge kidney
- Typically found in children or adolescents; not found at birth
- Ectasia of the papillary collecting ducts of one or more renal pyramids
- Renal function is normal
- Rare progression to end-stage renal disease
