LWBK1006-19 LWW-Govindan-Review December 7, 2011 21:24
Chapter 19•Neoplasms of the Mediastinum 225justifiable in patients whose performance status or comorbidities preclude
potentially curative combined modality therapy. Although there are some
data supporting the use of definitive chemotherapy plus radiotherapy
without surgical resection, further studies are needed to define the utility
of this approach.Answer 19.9. The answer is D.
In patients with thymic carcinoma, improved survival has been correlated
with the following histologic features: negative margins/complete resec-
tion, encapsulated tumors, lobular growth pattern, low mitotic activity,
and low histologic grade. Low-grade tumors include well-differentiated
squamous cell carcinoma, well-differentiated mucoepidermoid carcinoma
and basaloid carcinoma. High-grade thymic tumors include small cell car-
cinoma, poorly differentiated lymphoepithelioma-like carcinoma, sarco-
matoid carcinoma, anaplastic carcinoma, and clear cell carcinoma.Answer 19.10. The answer is C.
This young man with MEN I presented with a localized anterior mediasti-
nal mass. Thymic carcinoid is a rare tumor that is associated with MEN
I. Thymic carcinoids can produce adrenocorticotropic hormone (ACTH),
leading to Cushing’s syndrome, but rarely cause classical, serotonin-
induced carcinoid syndrome. The primary treatment is complete surgi-
cal resection, which results in a 5-year survival rate of 60%, although
late recurrences and mortality are not uncommon. Adjuvant radiother-
apy is reserved for patients with incomplete resections, and the role of
chemotherapy is unclear. Thymolipomas are rare, benign tumors that
occur mainly in young adults and consist of mature thymic and adipose
tissue. Although they are noninvasive, thymolipomas can grow to a large
size and cause symptoms resulting from compression of mediastinal struc-
tures. Complete resection is curative. Thymoma is not associated with any
of the MEN syndromes. Malignant islet cell tumors tend to recur locally
in the pancreatic bed or to metastasize to the peritoneum, regional lymph
nodes, and liver.Answer 19.11. The answer is C.
This young man presents with an anterior mediastinal mass and an ele-
vated-fetoprotein (AFP) that is pathognomonic for an NSGCT. Germ
cell tumors account for 10% to 12% of all mediastinal tumors in adults
and 6% in children and usually arise in the anterior mediastinum. Approx-
imately 10% of germ cell tumors originate in extragonadal sites, with
50% to 70% of these arising in the mediastinum. Serum tumor markers,
namely, LDH, AFP, and-hCG, are helpful in the diagnosis and manage-
ment of germ cell tumors. Benign teratomas, the most common mediasti-
nal germ cell tumors (60% to 70%), are not associated with significant
tumor marker elevations. Pure seminoma can cause modest elevations of
-hCG, but not AFP. AFP is produced by yolk sac elements, and in the set-
ting of a mediastinal mass, an elevated serum AFP level is pathognomonic
of NSGCT. Although lymphoma is commonly associated with elevations
of LDH, AFP is not affected.