Pediatric Tumors
Microscopically, it is characterized by large cells with marked
atypias, some of them similar to Langerhans cells. Identification
of Birbeck granules is critical for establishing the diagnosis.28
Breast Tumors
Breast tumors are infrequent in children, and most of them
affect adolescents and are benign. The most frequent are fibro-
adenomas (50-60% ), gynecomastia (10-15%), and fibrocystic
changes and cysts (5-10%). They almost always manifest as a
single, asymptomatic, slow-growing tumor. Benign phyllodes
tumor, hamartoma, hemangioma, lipoma, granule cell tumors,
fibroma, fibromatosis, papillary adenoma, and papilloma are
rare. Malignant breast neoplasms are very infrequent in children
(< 1% of tumors); the most frequent are secretory carcinoma
(juvenile carcinoma) and ductal and lobular carcinoma. Sarco-
mas are extremely rare. Sometimes non-neoplastic pathologic
processes can form a breast tumor, such as abscesses, hematomas,
galactoceles, adiponecrosis, and scar fibrosis.29 FNA is indicated
in palpable tumors, and it is recommended to use ultrasono-
graphic guidance. When combining FNA, clinical examina-
tion, and ultrasonography, a great diagnostic yield is obtained,
with sensitivity and negative predictive values of about 100%
and specificity > 50%. FNA can also be therapeutic in cysts and
Fibroadenoma is the most frequent breast tumor in children
and adolescents (> 50% of mammary tumors in this age group).
Fibroadenomas are almost always single and slow-growing.
Biphasic tumor develops in the terminal duct-lobular unit by
the influence of estrogen. Macroscopically, it is a well-defined
tumor, lobulated or smooth, elastic, and often 2-5 cm in diam-
eter. When it reaches a great size (> 15 cm), it is termed
Skin can be tense and erythematous with an
"orange peel" appearance and with prominent and distended
veins (Fig. 29.7A,B). Microscopically, stroma and epithelial
components vary in composition and cellularity, defining the
intracanalicular or pericanalicular type (Fig. 29.7C). Juvenile
fibroadenoma is clinically and macroscopically similar to giant
fibroadenomas, but it affects younger patients. When dissected,
it is multinodular and microscopically similar to the intracanali-
cular fibroadenoma. Periductal stroma is fusocellular without
atypias, with scarce mitoses, and with occasional fibrosis.29
Fine-needle aspirates of fibroadenomas usually show diagnos-
tic cytologic characteristics, high cellularity, and a mixture of
epithelial, stromal, and myoepithelial cells. Epithelial cells are
arranged in bidimensional sheets with well-defined edges and
are sometimes ramified (antler horn); they have uniform round
nuclei with thin chromatin and poorly visible nucleoli. Myoepi-
thelial cells are seen over epithelial sheets and apocrine cell
groups, and foamy macrophages can sometimes be observed.
In the background are epithelial and spindle cells with very
scarce cytoplasm that are occasionally seen at the nuclear poles
(Fig. 29.7D). Occasionally, there are fragments of hypercellu-
lar stroma in adolescents, especially in giant fibroadenomas.
Differential diagnosis between giant and juvenile fibroadenoma
and benign phyllodes tumor can be very difficult and some-
times cytologically impossible. Phyllodes tumor affects older
girls, grows faster than juvenile and giant fibroadenoma, and is
also more vascularized to eco-Doppler studies, which helps to
differentiate between them.30
Key features of fibroadenoma
• H ig h and heterog eneous c e llu la rity ;
• M ix tu re o f e p ith e lia l, s tro m a l, a nd m y o e p ith e lia l cells;
• E p ith e lia l cells in b id im e n s io n a l sheets;
• M y o e p ith e lia l cells o ver e p ith e lia l sheets; and
• S p in d le cells in th e b ackg round .
Gynecomastia is the most frequent breast tumor in adolescents
exposed to a decreased ratio of androgen to estrogen. These
tumors are mostly idiopathic and rarely associated with endocrine
anomalies (2-3% of cases), drugs, and other factors. Clinically, it
manifests as an increase in size and consistency of the breast.
Microscopically, it shows proliferation of breast ducts in
loose connective tissue stroma. The ducts are often branching
and are lined by one or two layers of cuboid cells.29
Aspirates are similar to findings in fibroadenoma: sheets of
cuboid ductal cells and fragments of loose connective tissue
Key features of gynecomastia
• M ix tu re o f e p ith e lia l, s tro m a l, a nd m y o e p ith e lia l cells;
• E p ith e lia l cells in b id im e n s io n a l sheets; and
• Few sp in d le cells in th e b ackg round .
Fibrocystic changes and cysts
Clinically, fibrocystic changes and cysts show up with a poorly
defined breast enlargement and a heterogeneous radiology that
can show single or multiple cysts. Microscopically, the condition
shows proliferation of the ductal epithelia, ductal hyperplasia
(adenosis), sometimes sclerosing, myoepithelial cell prolifera-
tion, and stromal fibrosis. Cysts are covered by a flat or metaplas-
tic apocrine epithelium.29 Fine-needle aspirates show moderate
cellularity, great bidimensional sheets of normotypic ductal cells
with occasional nuclear overexposition, clusters, sheets, and
papillary groups of apocrine cells, foamy macrophages, debris
in the background, and occasional appearance of myoepithelial
cells overlying ductal sheets. Cytology of cysts is slightly cellu-
lar, with much debris, foamy macrophages, and apocrine and
myoepithelial cells.30
For the key features of fibrocystic changes, see Chapter 25
Vascular Tumors
Vascular tumors are infrequent in the breast of children, and
there is a wide spectrum of vascular tumors, of which the
capillary hemangioma is the most frequent and whose FNA is
described in the discussion of soft tissue tumors.29
Carcinoma is very rare in children. The most frequent is secre-
tory carcinoma (juvenile carcinoma). It is often a well-defined
tumor, firm and small (1-2.5 cm), that appears beneath the
nipple. Microscopically, it is formed by nests of neoplastic
epithelial cells separated by bands of connective tissue. There
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