SP Web 7-2-09
Case 1:
History: 40 year-old female with diarrhea following treatment of pneumonia.
Your Diagnosis:
a) Ulcerative colitis
b) Crohn’s disease
c) Collagenous colitis
d) Pseudomembranous colitis
Answer: D
Description: The colectomy specimen demonstrates a mucosal necrosis pattern,
including epithelial cell necrosis, fibrin in the lamina propria, and pseudomembranes
formed by fibrin, mucus, degenerating neutrophils and degenerating epithelial cells.
While this morphology may be seen in patients suffering with ischemia or E. coli
0157:H7 infection, the morphology is typical of antibiotic-associated pseudomembranous
colitis caused by C. difficile.
Differential Diagnosis: Ulcerative colitis and Crohn’s disease would demonstrate signs
of a chronic colitis; i.e., crypt distortion, crypt atrophy, and metaplasia. Collagenous
colitis does not demonstrate the marked activity and mucosal necrosis seen in
pseudomembranous colitis.
Severe C. difficile colitis may result in full thickness mucosal necrosis and toxic
megacolon, requiring colectomy as was the case here.
Case 2:
History: 43 year-old female with a 7 cm adrenal mass
Your Diagnosis:
a) Granulocytic sarcoma
b) Myelolipoma
c) Diffuse Large B Cell lymphoma
d) Adrenal cortical carcinoma
Answer: B
Description: Within the adrenal there is a highly cellular proliferation of normal
hematopoetic elements associated with fat. One sees megakaryocytes, a spectrum of
maturing granulocytes, and islands of erythroid precursors. These are the typical features
of a myelolipoma.
Differential Diagnosis: Granulocytic sarcoma would feature sheets of primitive
granulocytic cell precursors. Diffuse large B-cell lymphoma would feature sheets of
pleomorphic lymphocytes with irregular nuclear contours and prominent nucleoli.
Adrenal cortical carcinoma would demonstrate more polygonal cells with eosinophilic
cytoplasm, reminiscent of the cytology of the normal adrenal cortex. Adrenal cortical
carcinoma demonstrates cytologic atypia, and characteristically shows vascular and
capsular invasion.
Myelolipomas which are fat-poor, like the current case, are often difficult to distinguish
from other adrenal lesions by imaging.
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Case 3:
History: 21 year-old male with a bladder polyp
Your Diagnosis:
a) Polypoid cystitis
b) Inflammatory myofibroblastic tumor
c) Botryoid embryonal rhabdomyosarcoma
d) Eosinophilic cystitis
Answer: C
Description: Much of this fragmented biopsy is histologically bland, and could pass for
an inflammatory polyp in that the stroma is myxoid and the cells do not show cytologic
atypia. However, in other areas of the biopsy there is condensation of primitive stromal
cells beneath the epithelium, forming a so-called “cambium-layer.” These primitive cells
have wisps of eosinophilic cytoplasm, and were immunoreactive for myogenin and
desmin on immunostains.
Differential Diagnosis: Polyp formations are often seen in patients with cystitis,
particularly in association with a stent. Inflammatory myofibroblastic tumor (IMT) would
not demonstrate immunoreactivity for Myogenin, and often labels for ALK. The cells of
an IMT generally have more hypochromatic nuclei than those of a rhabdomyosarcoma.
Eosinophilic cystitis may be seen in patients with allergic conditions; however, in most
cases eosinophilic infiltration of the bladder is secondary to a prior biopsy. Eosinophilic
cystitis would not show the spindle-cell proliferation seen in the current case.
Botryoid embryonal rhabdomyosarcoma is associated with a favorable prognosis relative
to other subtypes of rhabdomyosarcoma.
Case 4:
History: 74 year-old male with cirrhosis and liver mass
Your Diagnosis:
a) Hepatocellular carcinoma
b) Hepatocellular adenoma
c) Focal nodular hyperplasia
d) Regnerative nodule
Diagnosis: A
Description: The background liver shows areas of steatosis, and foci of regenerative
hepatocyte nodules surrounding by fibrosis. Cirrhosis was better developed in other parts
of the liver. The neoplasm consists of thickened trabeculae of hepatocytes. The trabeculae
are often over 5 cells in thickness, and the cells demonstrate a high nucleus to cytoplasm
ratio, pleomorphism, and readily identifiable mitotic figures. The cytoplasm is
eosinophilic and granular and resembles that of the non-neoplastic hepatocytes. These are
the typical features of hepatocellular carcinoma.
Differential Diagnosis: Hepatocellular adenoma is a diagnosis which should not be
made in the presence of significant cytologic atypia and mitotic figures. It is typically
seen in young females who are taking oral contraceptives. Focal nodular hyperplasia
features bile duct proliferation in association with benign hepatocytes, and essentially
resembles cirrhosis (hence the old terminology, focal cirrhosis). Regenerative nodules in
cirrhosis may feature expansions of hepatocytes, but the trabeculae should be 2 cells thick
or less, and significant cytologic atypia should not be present.
Case 5:
History: 63 year-old female with a lung mass.
Your diagnosis:
a) Bronchioloalveolar carcinoma
b) Micropapillary carcinoma
c) Atypical adenomatous hyperplasia
d) Usual interstitial pneumonia
Answer : B
Description: An ill-defined nodule is present within the lung, and it demonstrates central
elastosis. At the periphery, one sees atypical pneumocytes lining thickened alveolar septa.
At high power, one sees tufts of atypical pneumocytes projecting into distorted alveolar
spaces. These tufts demonstrate marked cytologic atypia, and lack fibrovascular cores.
This is the typical architecture of a micropapillary carcinoma.
Differential Diagnosis: Bronchioloalveolar carcinoma will feature atypical pneumocytes
lining essentially intact, thin alveolar septa. The micropapillary projections seen in the
current case should not be present. Atypical adenomatous hyperplasia would feature
small (usually less than 5 mm) areas of atypical pneumocytes with minimal cytoplasm
lining intact alveolar spaces. The advanced cytologic atypia seen in the current case
would not be present. It is always important to consider usual interstitial pneumonitis
before diagnosing a pulmonary adenocarcinoma. One may see cytologic atypia, often
accentuated on frozen section, in areas of UIP with honeycomb change. In this case, the
absence of cilia and the advanced cytologic atypia, along with the absence of other
typical features of UIP (such as fibroblast foci, honeycomb change, or temporal
heterogeneity of inflammatory changes), exclude this diagnosis.
Micropapillary carcinomas may be seen in a variety of organs. Common sites include the
breast, lung, bladder and salivary gland. This morphology is associated with high-stage in
all sites.
Reference: Adv Ant Pathol 2004; 11:297-303.
Case 6:
History: 77 year-old female with an endobronchial lung mass
Your diagnosis:
a) Carcinoid tumor
b) Atypical carcinoid tumor
c) Large cell neuroendocrine carcinoma
d) Small cell carcinoma
Answer: A
Description: This is an endobronchial mass which protrudes into the lumen of the
bronchus without overlying epithelium. The neoplastic cells grow in ribbon-like,
trabecular pattern. While the lesion appears to be highly cellular at low power, at high
power one can appreciate the uniform, “salt & pepper” chromatin of the neoplastic cells.
Mitotic figures are extremely scant (less than 2 per 50 high power fields), and there is no
necrosis. These are the typical features of a pulmonary carcinoid tumor.
Differential Diagnosis: Atypical carcinoid tumor would feature either an increased
mitotic rate or foci of necrosis. Large cell neuroendocrine carcinoma and small cell
carcinomas are high-grade carcinomas, so they typically feature extensive necrosis and
mitotic rates greater than 1 per high power field. Small cell carcinoma features fusiform
cells with hyperchromatic nuclei that show nuclear molding, while large cell
neuroendocrine carcinoma features polygonal cells with vesicular chromatin and
prominent nucleoli.