Myoid Harmatoma of the Breast: Clinicopathologic Recurrence Potential

LETTER TO THE EDITOR
Myoid Harmatoma of the Breast: Clinicopathologic
Analysis of a Rare Tumor Indicating Occasional
Recurrence Potential
To the Editor:
Myoid hamartoma (MH) is an extremely rare subtype of breast hamartoma characterized by the presence of myoid cell bundles in the stroma. Only
approximately 30 cases have been reported to date. So
its biological behavior, clinicopathologic features and
histological origin are not well characterized. Moreover, its potential recurrence is usually overlooked. To
the best of our knowledge, no case of MH with local
recurrence has been reported previously. Herein, we
described clinicopathologic features of five MHs, containing two recurrent lesions. Our aim is to elucidate
pathologic features of MH, and to lay stress on its
recurrence potential to evoke attentions of pathologists and surgeons.
Five cases of MH were collected in the Department
of Pathology, Shanghai Cancer Center, Fudan University, Shanghai. For each case, sections of 5 lm were
cut from paraffin blocks for HE and immunohistochemistry using Envision method. The primary antibodies included vimentin, desmin, h-caldesmon,
calponin, SMA, MSA. One case was studied ultrastructurally.
The age of five patients ranged from 29 to
44 years (mean, 39 years). Physical examinations all
revealed nontender, palpable lumps. The radiological
information of two patients was available. On Mammography, two lesions appeared as ovoid to rounded,
well circumscribed masses of mixed heterogenous
density. A thin smooth capsule with peripheral radiolucent zone was seen in one lesion. In MRI, the lesion
displayed an ovoid, well-defined mass with heterogenous enhancement, a focal dark thin rim. Internal fat
Address for correspondence and reprint requests to: Wentao Yang, MD,
PhD, Department of Pathology, Shanghai Cancer Center, Fudan University,
270 Dong’an Road, Shanghai 200032, China, or e-mail: [email protected]
yahoo.com.
DOI: 10.1111/j.1524-4741.2011.01085.x
ª 2011 Wiley Periodicals, Inc., 1075-122X/11
The Breast Journal, Volume 17 Number 3, 2011 322–324
intensity was demonstrated. All patients underwent
lumpectomy. Three patients were well after the initial
surgery. However, two cases developed local recurrence. One case relapsed 10 months following the initial surgery. Another recurred twice, with an interval
of 36 and 41 months, respectively. Moreover, when
recurred for the second time there were two separate
lesions. The two original tumors were ill-defined. All
patients were fine at present.
The lesion size ranged from 1.4 to 2.0 cm (mean,
1.7 cm). Gross examination all revealed round, ovoid,
soft or firm, nodular masses. Microscopically, three
lesions were sharply demarcated, with an intact, thin,
fibrous envelope. Two cases were ill-defined (Fig. 1).
Each lesion was composed of breast lobules and ducts,
myoid cell bundles, fibrous stroma, and mature adipose in various proportions. In one case, myoid component mingled more diffusely with adipose and
fibrous tissue, exhibiting solid sheet appearance. In the
remaining four cases, myoid element was scattered
within the fibro-fatty background. Myoid cells,
arranged in bundles or fascicles, showed the morphological appearance resembling smooth muscle cells or
myofibroblasts. In two cases, myoid cells apparently
arised from the myoepithelial layer of glands and
merging with it. In all lesions, adipose tissues were
noted in variable amounts, ranging from 5% to 20%
in area. Associated epithelial changes included apocrine metaplasia, and usual or papillary hyperplasia of
ductal epithelium. Neither epithelial cells nor stromal
cells had prominent atypia. Mitotic figures were
absent in four cases. Whereas, a few mitotic figures
(1 ⁄ 10HPF) were found in myoid stroma of one recurrent tumor (Fig. 2).
The immunohistochemical investigations revealed
that myoid component was diffusely and strongly
positive for vimentin, SMA and MSA in all tumors.
All cases showed variable expression of desmin. Three
cases were immunoreactive to h-caldesmon (Fig. 3)
and calponin, respectively. Ultrastructural study of
one case showed that there were large amounts of
letter to the editor • 323
Figure 1. The lesion was ill-defined, and mingled with the surrounding normal tissue in some area (HE stain).
Figure 3. Myoid stroma was positive for h-caldesmon (immunoperoxidase stain).
Figure 2. A few mitotic figures were found in myoid stroma (HE
stain).
Figure 4. Ultrastructural features. Myoid cells showed myofibroblastic differentiation, including cytoplasmic actin filaments with fusiform dense bodies, prominent subplasmalemmal densities and a
continuous basal lamina. No desmosomes or cytokeratin filaments
were seen.
cytoplasmic actin filaments with fusiform dense bodies
and abundant organelles. Prominent subplasmalemmal
densities and an almost continuous basal lamina were
also seen (Fig. 4). No desmosomes or cytokeratin filaments were indentified. These features were suggestive
of myofibroblastic differentiation.
The histogenesis of myoid component in MH is
uncertain. Different studies have raised that myoid
cells originate from myoepithelium, stromal myofibroblasts, walls of blood vessel, and stromal stem cell (1),
respectively. In this series, three lesions showed immunohistochemical traits of virtual smooth muscle
tumors. However, one case ultrastructurally exhibited
myofibrobalstic differentiation. So we propose that
myoid stroma expresses smooth muscle markers
immunohistochemically, while some tumors might
show myofibroblastic differentiation ultrastructurally.
The disparity of immunophenotype and ultrastructure
of myoid cell makes it difficult to judge its differentiation direction. More studies are needed to ascertain
the origin of myoid component.
Although breast hamartoma is benign, rare cases
with local recurrence have already been reported.
Daya et al. (2) noted that two of 25 cases recurred
after local excision, because the first resection was
incomplete. In the series of Tse et al. (3), one lesion
also developed recurrence. An incomplete excision
324 • letter to the editor
may be one contributing factor of tumor recurrence.
Some author (4) deems that there is no tendency local
recurrence or multifocality in MH. Nevertheless, in
this series, two cases developed local recurrence; one
initial tumor exhibited ill-defined with a few mitotic
figures. On these grounds, we presume these histological features might be suggestive of potential recurrence
of MH. Unsatisfactorily, it was difficult to judge the
status of surgical margins from the submitted tissue
sections, so we could not rule out the possibility of
incomplete resection leading to tumor recurrence.
Herein, we suggest that pathologists who see illdemarcated border and mitotic figures in myoid component should be alerted to recurrence possibility in
MH. Furthermore, it is essential to illustrate these
morphological findings in pathological reports, in
order to evoke attention of clinicians.
Although the recurrence possibility of hamartoma
was mentioned in literatures, surgeons have not paid
enough attentions to the issue in practice. Nowadays,
‘‘Shelling out the tumor’’ is still widely applied as the
routine treatment protocol. Some author (4) suggests
excisional biopsy performed by ‘‘shelling out’’ the
tumor is an adequate treatment for MH. However,
our study has demonstrated MH does have occasional
recurrence potential, so wide local excision and clear
margins should be warranted.
Lin Yu, MD,*
Wentao Yang, MD, PhD,*
Xiaoli Xu, MD, PhD,*
Yajia Gu, MD, PhD, Chaofu Wang, MD, PhD,*
Hongfen Lu, MD,*
Weiqi Sheng, MD, PhD,*
and Daren Shi, MD, PhD,*
*Department of Pathology, Fudan University Shanghai
Cancer Center, Fudan University, Shanghai, China
Department of Oncology, Shanghai Medical College,
Fudan University, Shanghai, China; and àDepartment
of Diagnostic Radiography, Fudan University
Shanghai Cancer Center, Shanghai Medical College,
Fudan University, Shanghai, China
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