THE CASE:
A 59-year-old man, heavy smoker, with no medical history, who consulted
for a sternal swelling starting from July 2019. The patient firstly
consulted in November 2019.Systemic symptoms as fever, night sweating or
weight loss were absent. The clinical examination revealed a firm
painful mass of the manubrium. There were no inflammatory signs of the
skin. A first chest computed tomography (CT) revealed a poorly limited
osteolytic lesion of the manubrium measuring 20 x 13 x 40 mm with
multifocal interruption of the anterior and posterior bony cortex. There
was a deep extension to the mediastinal tissue as well as to superficial
layers (figure 1). This scannographic aspect was very evocative of a
chondrosarcoma. Computed tomographic scans of the head, abdomen, and
pelvis did not reveal any suspicious lesion. There was no biological
inflammatory syndrome and LDH rate was normal. Tuberculosis tests were
negative, excluding a tuberculosis destruction of the sternum. A needle
biopsy was realized and concluded to a non-specific inflammatory
remodeling of striated muscle tissue. Unfortunately, it was not possible
to continue the follow up because of COVID-19 epidemic, and the patient
was lost of sight for 3 months. Meanwhile, the sternal mass increased in
size and become more painful. A second CT scan showed a progression of
the tumor (48 x 40 x 58mm) with a near contact with the brachiocephalic
vein truncus (figure 2). After multi-disciplinary team discussion, and
taking into consideration the high suspicion of a progressing sarcoma,
it was decided to perform a surgical resection of the mass. Via a median
skin incision facing the sternum, resection considered the whole
manubrium with an extension to the upper part of the body of the
sternum, the interior part of the clavicles and the anterior arch of the
two first ribs from both sides. In the anterior mediastinum, there was a
tight adhesion to the thymus and so resection was enlarged to this
later. Reconstruction was performed with a polytetrafluoroethylene
(PTFE) mesh and covered by the two pectoralis major (figure 3).
Postoperative course was uneventful. On macroscopy, manubrium was
enlarged and the cut surface was white, homogeneous. The cortical bone
was deformed with focal rupture. The posterior tissue contained lymph
nodes measuring 5 mm to 3cm. Histological examination revealed sternal
and lymph nodes infiltration by sheets of large round cells with scanty
cytoplasm and round nuclei containing 2 or 3 nucleoli; mitoses were
numerous. There was no chondroid differenciation. Immuno-histochemical
staining showed high and diffuse positivity for CD20 and CD79a (Figure
4). Margins were negative. Prospectively, no secondary location is found
and sternal location is the unique site. Level of LDH was normal. Based
on morphologic finding and clinical findings (a single skeletal site
with regional lymph node involvement), a primary B large cell lymphoma
of sternum was posed. This tumor was staged IIE, and the patient
received 6 cycles of R-CHOP protocol.