LWBK1006-19 LWW-Govindan-Review December 7, 2011 21:24
226 DeVita, Hellman, and Rosenberg’s CANCER: Principles and Practice of Oncology ReviewAnswer 19.12. The answer is C.
Although benign teratomas occur with equal frequency in men and
women, approximately 85% of malignant mediastinal germ cell tumors
occur in men. Primary pure seminoma accounts for only 35% of malig-
nant mediastinal germ cell tumors. Patients with pure seminoma may have
modest elevations of serum-HCG, but an elevated serum-fetoprotein
level indicates the presence of an NSGCT component, even in a patient
with biopsy-proven seminoma. Mediastinal NSGCTs carry a poorer prog-
nosis than testicular NSGCTs. All patients with mediastinal NSGCT are
considered poor-risk per the International Germ Cell Consensus Classifi-
cation, with 85% to 95% having distant metastases at presentation. The
overall 5-year survival rate of patients with mediastinal NSGCT is about
50%.Answer 19.13. The answer is A.
This woman has undergone complete resection of a tumor with radiologic
and histologic characteristics of a benign, noninvasive teratoma. Benign
teratoma is the most common mediastinal germ cell tumor. Unlike malig-
nant germ cell tumors, benign teratomas, also known as dermoid cysts,
occur with equal incidence in both men and women, primarily affecting
patients between 20 and 40 years of age. Benign teratomas frequently
present as large anterior mediastinal masses with normal serum tumor
markers that cause symptoms resulting from compression of mediasti-
nal structures. Although they may be adherent to adjacent structures,
they are typically noninvasive. Histologically, both benign and malig-
nant teratomas contain elements from all three germ cell layers: ectoderm
(skin, hair, sweat glands, teeth); mesoderm (fat, muscle, bone, cartilage);
and endoderm (bronchial or intestinal epithelium). Malignant teratomas,
in which one or more of these elements have an invasive or metastatic
phenotype, are aggressive tumors that usually have a poor response to
therapy and are associated with an unfavorable prognosis. In contrast,
surgical resection of benign teratoma results in excellent long-term sur-
vival rates with a low risk of recurrence. Neither adjuvant radiotherapy
nor chemotherapy is indicated in the management of patients with benign
teratoma.Answer 19.14. The answer is B.
This young man presents with a mediastinal poorly differentiated car-
cinoma of unknown primary site that is clinically and molecularly
consistent with an extragonadal germ cell tumor. Poorly differentiated
carcinoma arising in the midline structures of a young man is highly sug-
gestive of an unrecognized extragonadal germ cell tumor, even in the face
of normal tumor markers. In this patient, immunohistochemical analysis
is suggestive of carcinoma with positive cytokeratin and argues against
lymphoma (common leukocyte antigen), neuroendocrine tumor (chromo-
granin), sarcoma (vimentin), lung cancer (TTF1), and melanoma (S100).
Genetic analysis can frequently be useful in clarifying histogenesis in such
situations. Isochromosome 12p (i[12p]) is pathognomonic of germ cell