Ewing-Like Adamantinoma

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Orthopaedics & Traumatology: Surgery & Research (2012) 98, 845—849

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CASE REPORT

Ewing-like adamantinoma

a,∗ a a b a

M.M. Hamdane , L. Charﬁ , M. Driss , H. Nouri , R. Sellami-Dhouib ,

a b a

K. Mrad ,M. Mestiri , K. Ben Romdhane

Histopathology Department, Salah Azaiez Institute, Bab Saâdoun, 1006 Tunis, Tunisia

Adult Orthopaedics Department, Mohamed-Kassab Orthopaedics Institute, Ksar Saïd, 2010 Mannouba, Tunisia

Accepted: 6 June 2012

KEYWORDS Summary The Ewing-like variation of adamantinoma is a rare entity, leading to challenge its

Adamantinoma; differential diagnosis, notably with Ewing’s sarcoma. We are reporting a case of a 20-year-old

Sarcoma; male who presented with swelling in the left leg that had progressed over a 2-year period. X-rays

Ewing; revealed a tumour in the tibia that was intracortical, osteolytic, multilocular and invaded the

Pathology; soft tissues. A surgical biopsy was performed. Histopathology examination showed a tumour

Immunohistochemistry growth with small round cells expressing CD99. A diagnosis of Ewing’s sarcoma was made.

Since the patient declined surgical treatment, chemotherapy was administered. Tw o years later,

the patient returned because the tumour had grown in size. A second biopsy was performed.

Microscopic evaluation showed a tumour growth with osteoﬁbrous and epithelial components,

which expressed pankeratin and vimentin, but was negative for CD99. A diagnosis of Ewing-like

adamantinoma was made.

Introduction We are reporting here on a rare case of Ewing-like adamanti-

noma.

Adamantinoma is a rare bone tumour in young adults that

usually affects the diaphysis of the tibia. This is a low-grade, Observation

malignant tumour, which histologically appears as a biphasic

tumour with intermingled epithelial and osteoﬁbrous com-

This is the case of a 20-year-old male who presented with

ponents. A differential diagnosis with other lesions (both

swelling on the anterior aspect of the left leg, which had

benign and malignant) can be challenging to make based

become more evident over a 2-year period. Clinical exam-

only the histopathology. The diagnosis is even more

ination revealed a soft, painless swollen area, 5 cm in

challenging when this growth looks like a round cell tumour.

diameter, on the anterior aspect of the left leg, without signs

of inﬂammation or satellite lymphadenopathy. Standard X-

rays showed an intracortical, osteolytic, multilocular lesion

∗

with peripheral sclerosis on the anterior tibia that extended

Corresponding author. 60, avenue Bahi-Ladgham, Ennasr 2, 2037

Ariana, Tunisia. Tel.: +216 52 26 75 77. forward into the soft tissues and had a vacuolar, ‘‘soap-

E-mail address: [email protected] (M.M. Hamdane). bubble’’ like appearance. MRI showed an aggressive tumour

846 M.M. Hamdane et al.

Figure 1 MRI: a: frontal reconstruction showing the surface

lesion without medullary canal involvement; b: T1 after gadolin-

ium injection: intracortical lesion invading the soft tissues and

increasing in intensity.

Figure 2 Swelling on the anterior aspect of the left leg.

starting from the anteromedial cortex of the tibia, invad-

ing most of the soft tissues, but not affecting the medullary

canal (Fig. 1).

A surgical biopsy was performed. Histopathology showed

a tumour growth with diffuse layers of small, round,

monomorphic cells, with little cytoplasm, a round nucleus

and thin chromatin. The stroma was ﬁbrous and highly vas-

cularized. Immunohistochemistry showed that the tumour

cells were intensely and diffusely stained for CD99 and

vimentin, and to a lesser degree for S100 proteins. Based

on these morphological and immunohistochemical fea-

tures, a diagnosis of Ewing’s sarcoma was made. The

patient underwent four rounds of chemotherapy. Amputa-

tion of the leg was then proposed to the patient, who

refused.

Tw o years later, the patient returned because the tumour

had increased in size. Physical examination showed a swollen

area, 17 cm in diameter, on the anterior aspect of the left

leg that was soft and slightly painful (Fig. 2). Standard

X-rays showed intracortical osteolysis with cortex rupture

and extension to the soft tissues (Fig. 3). MRI showed a

large superﬁcial lesion starting at the cortex with signiﬁcant Figure 3 Standard X-rays of the leg: intracortical, osteolytic

involvement of the soft tissues, having cavities separated lesion invading the soft tissues. Note the polycystic nature giv-

by T1 and T2 hyposignal partitions. These cavities had ing a ‘‘soap-bubble’’ appearance in the images and an ‘‘apple

ﬂuid-ﬂuid levels suggestive of associated aneurysmal cysts core’’ appearance that is easily seen on the X-ray (b).

(Fig. 4).

Based on the lengthy progression and radiological appear-

ance of the lesion, the diagnosis of Ewing’s sarcoma was

disputed. A second surgical biopsy was performed. Micro- CD99. A diagnosis of Ewing-like adamantinoma was then

scopic evaluation showed a tumour growth organized in made.

layers and streaks, within abundant ﬁbrous and collagenous No distant metastasis was found. The tumour was excised

stroma (Fig. 5). The tumour cells were basophilic, cohe- surgically as a whole block. Reconstruction was performed

sive, rounded, polygonal or fusiform. In some areas, clear with a translated ipsilateral vascularized ﬁbula; an external

epithelial differentiation was noted. There was moder- ﬁxator was used for stabilisation. The ﬁxator was removed

ate atypism and many mitotic cells. Immunohistochemistry after 1 year and a walking boot was used for the next 6

showed that the tumour cells expressed both keratin months. Three years after the surgery, the patient was doing

and vimentin (Figs. 6 and 7) and were negative for well.

Ewing-like adamantinoma 847

Figure 5 Tumour growth, epithelial in nature, organized in

layers and streaks, within abundant ﬁbrous and collagenous

stroma (HE, 100 ).

Figure 6 Tumour cells expressing keratin (IHC, 400 ).

Figure 4 MRI: frontal reconstruction without (a) and with

(b) gadolinium injection and axial slice (c): polycystic corti-

cal lesion with changes to the medullary canal signal. Note the

appearance of the ﬂuid-ﬂuid level (c).

Figure 7 Tumour cells expressing vimentin (IHC, 200 ×).

848 M.M. Hamdane et al.

Discussion different morphological appearance than that of the initial

tumour: there was a predominant epithelial component, the

round cells had disappeared and there was no CD99 expres-

Adamantinoma is a rare, low-grade, malignant tumour that

sion.

consists 0.4% of all primary bone tumours and affects the

Treatment approaches for Ewing-like adamantinoma

diaphysis of the tibia in 85 to 90% of cases [1]. It can occur

have not yet been standardized, given how rare this entity

at any age, but mostly affects young adults (average age

is. In our reported case, the treatment approach was similar

of 25 to 35 years), with men being affected slightly more

to treatment of a classic adamantinoma; a wide resection

often than women [1]. Clinically, adamantinoma presents as

of the tumour was performed.

swelling of the leg that has slowly increased in size over time

and may or may not be painful [1]. X-rays usually show an

osteolytic, intracortical lesion, often having multiple parti- Conclusion

tions giving it a ‘‘soap-bubble’’ like appearance; the lesion

is surrounded by peripheral sclerosis [1]. Histopathology is The Ewing-like form of adamantinoma is a rare vari-

required for a positive diagnosis. Adamantinoma is char- ant. The aetiology of this pathology is not yet known.

acterized histologically by a biphasic growth with various The histopathology diagnosis is difﬁcult. However, when a

amounts of intermingled epithelial and osteoﬁbrous compo- tumour appears in the tibia of a young adult and has an

nents. In classic adamantinoma, the epithelial component intracortical location, a diagnosis of adamantinoma must

has four potential morphological variations: basaloid, tubu- be considered and further immunohistochemistry work must

lar, squamoid and spindle cell. A ﬁfth histological subtype be done to look for expression of epithelial markers. In

can be distinguished from classic adamantinoma and is char- the most challenging cases, molecular biology studies can

acterised by a large amount of osteoﬁbrous tissue. now be done on deparafﬁnised tissues, which would help

The Ewing-like form is a rare variant of adamantinoma, to differentiate between adamantinoma and Ewing’s sar-

with only ﬁve cases described in the published literature coma.

[2—5]. It is characterised by a growth of small, round,

uniform cells that express both epithelial and neural cell

Disclosure of interest

immunohistochemical markers, including those typical of

Ewing’s sarcoma (CD99+). These cells also have ultrastruc-

The authors declare that they have no conﬂicts of interest

tural characteristics of both epithelial and neuroendocrine

concerning this article.

cells [2,3,6,7].

The histogenesis of this tumour is not clear, but the

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