Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

epresenting tumour cells undergoing
pyknosis are prominent in some cases.
Mitotic figures may be numerous.
Though the nuclear to cytoplasmic ratio
is high, a rim of clear cytoplasm and discrete
cell membranes are often apparent
in well-fixed tumours without extensive
degenerative changes. The presence of
clear cytoplasm is often associated with
abundant glycogen as demonstrated by
diastase sensitive PAS-positivity.
Immunoprofile
The basic immunophenotype of PNET-
EWS, regardless of the primary site, is
the expression of vimentin and the surface
antigen of the MIC2 gene, CD99
(O13) or HBA-71. Approximately 20% of
cases also express pan-cytokeratin. The
staining pattern for vimentin and cytokeratin
may be perinuclear or Golgi zone
punctate reactivity.
Somatic genetics
Virtually all of the recently reported PNET-
EWSs have had the t(11;22)(q24;q12)
translocation with the fusion transcript
between the EWS gene (22q12) and the
ETS-related oncogene, FLI1 (11q24)
{1627,2124}. Variant translocations with
EWS are those with other ETS-related
oncogenes: (21q22), (7p22), (17q12)
and (2q33).
Prognosis
Pathologic stage is the major determinant
in the prognosis of PNET-EWS
regardless of the primary site.
Aggressive multidrug chemotherapy has
resulted in an improvement in the clinical
outcome {525}.
Fig. 1.128 PNET of the kidney. CD99 expression.
Table 1.12
Immunohistochemical differentiation of neuroectodermal tumours from other tumours with similar microscopic
features.
VIM CK CHR SYN NSE CD99 CD45 WT-1 CD117
PNET-EWS + +/– +/– +/– + + – – +
NB – – + + + – – – +
Carcinoid – + + + + – – – –
NEC – + + + + – – – –
NHL + – – – – +* + – –
Blastemal WT + + – – +/– – – + +
________
Abbreviations: PNET-EWS = primitive neuroectodermal tumour / Ewing sarcoma, NB= neuroblastoma,
NEC= neuroendocrine carcinoma, NHL= non-Hodgkin lymphoma, WT = Wilms tumour, VIM = vimentin,
CK = cytokeratin, CHR = chromogranin, SYN = synaptophysin, NSE - neuron specific enolase.
* CD99 is expressed by lymphoblastic lymphoma.
Neuroblastoma
D.M. Parham
ICD-O code 9500/3
Neuroblastomas arising as a true
intrarenal mass are extremely rare; only
six cases were identified in the National
Wilms Tumour Study Pathology Centre in
1993 {2225}. Pure intrarenal lesions
hypothetically arise from either adrenal
rests or intrarenal sympathetic tissue
{2385}. Far more frequently, adrenal neuroblastomas
invade the adjacent kidney;
this occurs in approximately five per cent
of cases {2375}. Because most neuroblastomas
arise from the adrenal, those
affecting the kidney predominate in the
superior pole. Extensive renal sinus invasion
may simulate a pelvic tumour.
Preoperative determination of urine catecholamine
excretion is helpful in diagnosis
of neuroblastoma but may not
exclude nephroblastomas with neural
elements {2273}. The presence of primitive
neural tissue defines neuroblastomas,
which contain Homer Wright
rosettes, neurofibrillary stroma, and
embryonal cells with round nuclei containing
granular, "salt and pepper" chromatin.
Important positive indicators of
neuronal differentiation include neuronspecific
enolase, synaptophysin, S100
protein, and chromogranin.
84
Tumours of the kidney