Adrenal cortical tumors, pheochromocytomas
Ricardo V Lloyd
Department of Pathology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
Distinguishing adrenal cortical adenomas from carcinomas may be a difficult diagnostic problem. The criteria of
Weiss are very useful because of their reliance on histologic features. From a practical perspective, the most
useful criteria to separate adenomas from carcinomas include tumor size, presence of necrosis and mitotic
activity including atypical mitoses. Adrenal cortical neoplasms in pediatric patients are more difficult to
diagnose and to separate adenomas from carcinomas. The diagnosis of pediatric adrenal cortical carcinoma
requires a higher tumor weight, larger tumor size and more mitoses compared with carcinomas in adults.
Pheochromocytomas are chromaffin-derived tumors that develop in the adrenal gland. Paragangliomas are
tumors arising from paraganglia that are distributed along the parasympathetic nerves and sympathetic chain.
Positive staining for chromogranin and synaptophysin is present in the chief cells, whereas the sustentacular
cells are positive for S100 protein. Hereditary conditions associated with pheochromocytomas include multiple
endocrine neoplasia 2A and 2B, Von Hippel–Lindau disease and neurofibromatosis I. Hereditary paraganglioma
syndromes with mutations of SDHB, SDHC and SDHD are associated with paragangliomas and some
Modern Pathology (2011) 24, S58–S65; doi:10.1038/modpathol.2010.126
Keywords: adrenal cortical adenoma; adrenal cortical carcinoma; paraganglioma; pheochromocytoma; succinic
Adrenal cortical tumors
The normal adrenal contains three zones in the
cortex (glomerulosa, fasciculata and reticularis),
whereas the adrenal medulla is located in the
central portion of the gland.
Adrenal cortical adenomas (Figure 1a) commonly
arise from the zona fasciculata, although all three
zones can give rise to benign or malignant tumors.
Adrenal cortical adenomas may be functioning or
nonfunctioning.1These tumors are usually positive
for melan A by immunostaining (Figure 1b).1Many
small adenomas o3cm in diameter are discovered
accidentally during working up for various other
conditions. These tumors are referred to as ‘inci-
dentalomas’. One of the major problems in diagnos-
tic endocrine pathology is distinguishing adrenal
cortical adenomas from carcinomas. This is espe-
cially true with borderline lesions compared with
small adenomas o20g or very large tumors 4500g
that are usually obvious carcinomas.
Adrenal cortical carcinoma may be functioning
malignancies in some cases, whereas in other cases
they are nonfunctioning.1–6The gross appearance of
adrenal cortical carcinoma can be very helpful in
making the diagnosis. Most carcinomas in adults are
4100g, whereas adenomas generally weigh 50g or
less. Adrenal cortical tumors weighing o50g have,
on occasion, metastasized, but this is extremely
uncommon. In pediatric patients, however, adrenal
cortical adenomas may weigh up to 500g. In
addition to tumor weight, the presence of necrosis
usually indicates an adrenal cortical carcinoma
unless the necrosis resulted from a traumatic insult
such as FNA. A variegated appearance with nodu-
larity and intersecting fibrous bands should also
suggest the possibility of a carcinoma.
Various studies have outlined specific criteria
used to diagnose adrenal cortical carcinomas.7–10
The criteria of Weiss8,9are most useful because of
their reliance on histologic features. These include
high nuclear grade, mitotic rate 45 per 50 HPF,
atypical mitotic figures, eosinophilic tumor cells
(Z75% of tumor), diffuse architecture (Z33% of
tumor), necrosis, venous invasion (smooth muscle
Received 9 June 2010; accepted 10 June 2010
Correspondence: Dr RV Lloyd, MD, PhD, University of Wisconsin
School of Medicine and Public Health, K4/814 Clinical Science
Center, 600 Highland Avenue, Madison, WI 53792, USA.
Modern Pathology (2011) 24, S58–S65
& 2011 USCAP, Inc. All rights reserved 0893-3952/11 $32.00
in wall), sinusoidal invasion (no smooth muscle in
wall) and capsular invasion8,9(Figure 2a and b).
Three or more of the nine criteria are indicative of
an adrenal cortical carcinoma, whereas two or less
would be more in keeping with an adenoma. The
modification of the Weiss system by Aubert et al10
has somewhat simplified the Weiss criteria. Other
systems such as that of van Slooten et al11attach
numeric values to the various criteria, and an index
of eight or higher was consistent with a carcinoma.
One of the older systems is that of Hough et al,12
who used histologic criteria and clinical parameters
in their assessment of adrenal cortical neoplasms. A
numeric value of 2.91 was indicative of malignancy,
whereas a value of 0.17 or less was consistent with a
benign lesion. The disadvantage of this system is the
reliance on clinical parameters as well as histologic
features, and some of these clinical parameters, may
not be available when examining the specimen.
From a practical perspective, the most useful
criteria to separate adenomas from carcinomas
include tumor size, presence of necrosis, mitotic
activity including atypical mitoses, invasive growth
and high nuclear grade. Capsular invasion may be
difficult to recognize because the expanding capsule
may be a preexisting adrenal capsule. Invasion of
adjacent soft tissue, kidney or liver is definitive sign
of malignancy. Special studies may be useful in
confirming the nature of the malignant tissue.13–19
Ultrastructural studies may show the distinct fea-
tures of ACC tissues including abundant smooth
endoplasmic reticulum and mitochondria with
prominent tubular or vesicular cristae. Immuno-
histochemical studies that are most useful in
adrenal cortical carcinoma include melan A, inhi-
bin-a and calretinin. Stains for cytokeratin are
strongly positive. Synaptophysin is usually weakly
positive in these tumors. Chromogranin is consis-
tently negative. A marker for adrenal cortical cells,
Ad4BP/SP-1, is relatively restricted in its distribu-
tion20,21and may be useful in the diagnosis of
Figure 1 Adrenal cortical adenoma. (a) The tumor is composed of relatively uniform cells without mitosis or necrosis. (b) Melan-A
immunostaining shows diffuse positive staining in the cytoplasm of the tumor cells.
Figure 2 Adrenal cortical carcinoma. (a) The tumor cells have large nuclei and prominent nucleoli. Prominent mitotic figures are seen.
(b) Confluent areas of necrosis are present in this adrenal cortical carcinoma.
Modern Pathology (2011) 24, S58–S65
adrenal cortical tissues. This protein is a transcrip-
tion factor that is needed for embryonic develop-
ment of adrenal cortical cells.
Adrenal cortical neoplasm in pediatric patients is
more difficult to diagnose and to separate adenomas
from carcinomas.22In a study of 83 adrenal cortical
neoplasms, only 31% of histologically malignant
tumors behaved in a clinically malignant manner.
Features of malignancy included tumor weight
4400g, tumor size 410.5cm, vena cava invasion,
confluent necrosis, periadrenal soft tissue invasion
415 mitoses per HPF and atypical mitoses.
There are several variants of adrenal cortical
tumors. The most common include the oncocytic
tumors,23,24and the myxoid variant.25Criteria for the
diagnosis of oncocytic carcinomas were recently
proposed by Weiss’ group.24Major criteria for
oncocytic tumors included high mitotic rate, atypi-
cal mitoses and vena cava invasion. Minor criteria
included large size and weight, necrosis, capsular
invasion and sinusoidal invasion. One major criter-
ion indicated malignancy, whereas 1–4 minor
criteria indicated borderline tumors. Absence of all
major and minor criteria indicated benign oncocytic
tumors. The myxoid variant of adrenal cortical
tumors looks different morphologically, but the
criteria for malignancy should be similar to conven-
tional adrenal cortical tumors.
The differential diagnosis of adrenal cortical
carcinoma includes renal cell carcinoma, hepatocel-
lular carcinoma, pheochromocytomas, and meta-
growth factor-2 has been useful in the classification
of adrenal cortical tumors.26
Recent studies of these various markers and
techniques separate adrenal cortical carcinomas
from adenomas. Some of these include DNA flow
cytometric analysis and nucleolar organizer regions
have not been very effective. However, some
markers of proliferation have been shown to be
useful in the distinction. Ki-67 labeling index with
MIB-1 antibody are somewhat promising.19,20
Molecular studies have characterized various genes
that are differentially expressed in normal and
benign compared with malignant adrenal cortical
tumors.27–31The phenotypes of Ki-67-negative, p53-
negative, mdm-2-positive, cyclin-D1-negative, Bcl-
2-negative, p21-negative and p27-positive cells were
found in 83% of normal adrenal tissues, but only in
3% of malignant tumors.27Giordano and collea-
gues28,29performed microarray analysis of adrenal
cortical tumors and reported upregulation of IGF2 in
10% of adrenal cortical carcinomas (90.9%). Pro-
liferation in related genes such as TOP2A and Ki-67
was also upregulated in carcinomas. Velazquez-
Fernandez et al30performed expression profiling of
7 patients with adrenal cortical carcinomas and 13
with adenomas and reported upregulation of ubi-
quitin-related genes (USP4 and UFD1L) and insulin-
like growth factor-related genes (IGF2, IGF2R,
IGFbP3 and IGFbP6). A cytokine gene (CXCL10)
and cadherin 2 gene (CDH2) were downregulated in
carcinomas compared with adenomas.30
Pheochromocytomas and paragangliomas
Pheochromocytomas (‘dusky colored tumor’) are
chromaffin-derived tumors that develop in the
adrenal gland.1When the tumor is immersed in
chromaffin salts or other weak oxidizing agents, it
develops the dusky color. Most tumors are sporadic
and benign. The reported incidence is about 0.4–9.5
per 106people. The tumors occur most frequently in
the fourth and fifth decades. Familial tumors
develop at a younger age. Most familial tumors are
bilateral, whereas sporadic tumors are unilateral.
Patients usually present with throbbing head-
aches, sweating, palpitations, chest and abdominal
pains. The ‘spells’ may last from 10 to 60min and
may be triggered by positional changes.
Pheochromocytomas usually form cell nests com-
posed of cells with abundant basophilic cytoplasm
(Figure 3a). Ultrastructural features include dense
core secretory granules (Figure 3b).
Malignant pheochromocytomas comprise only
about 10% of all pheochromocytomas. Signs and
symptoms are similar to these in patients with
benign disease; however, catecholamine production
and the degree of hypertension may be more marked
with metastatic disease.
Imaging studies cannot distinguish benign from
metastatic disease. CT studies and iodine-123-meta-
iodobenzyl-guanidine is very useful in imaging
especially for locally recurrent or metastatic disease.
Malignant pheochromocytomas tend to be larger
tumors than benign ones. They may be more nodular,
lobular and show areas of necrosis. They may infiltrate
periadrenal adipose tissue. Metastatic disease is the
most reliable evidence of malignancy.31–45
Histologic features suggesting malignancy include
capsular invasion, vascular invasion, extension into
periadrenal adipose tissue, diffuse growth, necrosis,
tumor cell spindling, increased cellularity, marked
nuclear pleomorphism, macronucleoli, increased
mitoses including atypical mitoses, absence or
decreased hyaline globules.
Sustentacular cells were reported to be decreased
or absent in malignant pheochromocytomas.1MIB-1
labeling index may be helpful in separating benign
and malignant pheochromocytomas. However, in
some larger studies using 2.5 or 3.0% of cutoff
points had a sensitivity of only 50% in identifying
proven malignant tumors.
Gland Scaled Score (PASS) was developed by
Thompson to distinguish benign from malignant
Modern Pathology (2011) 24, S58–S65
pheochromocytomas.46It uses features such as
growth pattern, necrosis, cellularity, cellular monot-
ony, tumor cell spindling, mitotic count, atypical
hyperchromasia to try to separate tumors. A PASS
of Z4 is associated with a higher probability for
malignancy. The use of the PASS was not validated
independently in a recent study by a group of
endocrine pathologists.47Other studies of malignant
pheochromocytomas have been recently report-
ed.34,48–50The proposed system of Kimura et al34
used an assigned score that adds up to a maximum
of 10 Ki-67 immunoreactivity along with catechola-
mine and phenotype. With a score of 7–10, 100% of
patients were found to have malignant tumors.34
Paragangliomas (PGLs) are tumors arising from the
paraganglia that are distributed along the parasym-
pathetic nerves in the head, neck and mediastinum,
and along the sympathetic chain such as the
cervical, intrathoracic, supraneural inferior paraaor-
tic and urinary bladder. Although morphologic
distinction between pheochromocytomas and PGLs
is difficult, molecular differences between tumors
arising in the adrenal medulla and other sites
are more evident. As to malignancy, the general
impression is that tumors arising in the organs of
Zuckerkandl close to the bifurcation of the aorta
have the highest incidence of malignancy.
Histopathologic features of pheochromocytomas
and PGLs include chief cells with basophilic to
amphophilic cells with abundant cytoplasm and
large vesicular nuclei (Figure 4a). A prominent
Zellballen or cell-nesting pattern may be present.
Some tumors may have scant cytoplasm. Cellular
and nuclear pleomorphism may be prominent.
Cytoplasmic hyaline globules are frequently present.
Melanin-like pigment may be present. Mitotic
figures are uncommon. Tumors may have scattered
ganglion cells, which does not indicate a composite
Immunohistochemical studies show that the chief
cells of the tumors are positive for chromogranin
(Figure 4b) and synaptophysin (Figure 4c). The
sustentacular cells are positive for S100 acidic
protein (Figure 4d). The absence of positivity for
EMA helps to distinguish pheochromocytomas
from renal cell carcinomas. Adrenal cortical tumors
are positive for melan A, inhibin-a and calretinin,
and weakly positive for keratin; but negative for
chromogranin A, whereas pheochromocytomas and
PGLs are positive for chromogranin A and negative
for melan A and keratins.
Pheochromocytomas associated with a variety of
inherited conditions including multiple endocrine
neoplasia type 2 (MEN2), Von Hippel–Lindau
(VHL) disease, neurofibromatous type 1 (NF1),
heredity PGL syndromes and Sturge–Weber disease.
The genetics of these disorders are summarized in
Multiple endocrine neoplasia type 2
Approximately 50% of patients with MEN2 develop
pheochromocytomas. De novo germ-line mutations
occur in about 6% of MEN2A and familial medul-
lary thyroid carcinoma cases and in around 50% of
Von Hippel–Lindau disease
The frequency of pheochromocytomas in VHL
patients ranges from 10 to 30% and is restricted to
the type 2 kindreds. Type 1 VHL patients with renal
cell carcinomas, hemangioblastomas and retinal
angiomas do not usually develop pheochromocytomas.
Neurofibromatosis type 1
Pheochromocytomas are associated with 1–4% of
NF1 patients. NF1 carries 100% disease penetrance
within families. The prevalence of pheochromocy-
tomas in NF1 patients is greater than that in the
Figure 3 Pheochromocytoma. (a) The tumor cells have abundant basophilic cytoplasm. A prominent cell-nesting pattern (Zellballen) is
noted. (b) Ultrastructural features of a pheochromocytoma with abundant secretory granules. The nonepinephrine-containing granules
have a halo between the dense core and the granule membrane.
Modern Pathology (2011) 24, S58–S65
Hereditary paraganglioma syndromes
(SDHB) and SDHD mutations in pheochromocyto-
mas is about 3–5%. These mutations are much more
common in paragangliomas or extra-adrenal pheo-
chromocytomas. SDHB mutations have been asso-
ciated with malignant paragangliomas (Table 1).
Paragangliomas in the retroperitoneum are more
likely to have SDHB mutations, and these are more
commonly associated with malignancy. SDHC mu-
tations are more common in head and neck
paragangliomas that are usually benign.52The most
recently described SDH mutation is SDHAF2.52The
gene responsible for this mutation (PGL2) was
initially termel SDHS.52
The distribution of genetic abnormalities between
familial and sporadic pheochromocytomas and
paragangliomas is also strikingly different.51Recent
studies have shown that immunohistochemical
screening can be used to detect germ-line mutations
of SDHB, SDHC and SDHD53with the use of the
antibodies reported by this group. DHAF2 mutations
are associated with tumors of the head and neck
The sporadic tumors
whereas tumors with germ-line mutations
negative (Figure 5a and b). Molecular sequencing
should be performed to validate the immunohisto-
The usual prognosis of malignant pheochromocyto-
mas is about 50%/5-year survival. Some patients
may have indolent disease with a life expectancy of
more than 20 years.
A series of molecular markers have been reported as
markers of malignancy in pheochromocytomas.38
These include heat shock protein 9.0, human
Table 1 Hereditary conditions associated with pheochromocyto-
mas and paragangliomas
Pheo PGL Genetics
MEN 2A and 2B
Von Hippel–Lindau 3p26-29
Neurofibromatosis I 17q11.2
Pheo, pheochromocytoma; PGL, paraganglioma; SDH, succinate
Figure 4 Retroperitoneal paraganglioma. (a) The H&E section shows tumor cells with moderate amount of cytoplasm and small nuclei.
(b) Chromogranin A immunostaining is diffusely positive in the tumor cells. Chromogranin A is present in the secretory granule.
(c) Synaptophysin staining shows diffuse cytoplasmic staining in the tumor cells. (d) S100 acid protein stains the sustentacular cells in
Modern Pathology (2011) 24, S58–S65
telomerase reverse transcriptase, vascular endothe-
lial growth factor, vascular endothelial growth factor
receptor hypoxia inducible factor 2-a, cyclooxygen-
ase 2, tenascin C, N cadherin- and secretogranin II-
derived peptide EM66. The practical application of
these markups will require more studies.
The Weiss criteria are commonly used to separate
adrenal cortical adenomas from carcinomas. Adre-
nal cortical neoplasms in pediatric patients are more
difficult to diagnose and it is more difficult to
separate benign from malignant tumors in this age
group. Oncocytic and myxoid variants of adrenal
cortical tumors are uncommon. Different criteria are
used to diagnose oncocytic adrenal cortical carcino-
mas. Pheochromocytomas and paragangliomas are
usually positive for chromogranin and synaptophy-
sin, whereas the sustentacular cells in both tumor
groups are positive for S100 protein. A careful
family history and molecular analyses are helpful
in the workup and diagnosis of familial pheochro-
mocytomas and paragangliomas. Mutations of the
SDH gene family are associated with hereditary
paraganglioma syndrome and SDHB mutations,
which occur more commonly in retroperitoneal
paragangliomas, are frequently associated
Disclosure/conflict of interest
The author declares no conflict of interest.
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