Discussion
We report here a case of IMOS in a 53-year-old man. To the best of our
knowledge, there are less than twenty cases reported in literature.
In the series of Kullanuch Chanchairujira and al, nine female patients
with leg pain and imaging signs of IMOS were detected during a 25-years
period [3]. Kensaku Abe and al reported three cases (one man, two
women) of osteosclerotic lesions (femoral diaphyses, tibial diaphysis)
examined between 2015 and 2019 [2]. Vasilios Skiadas and al
presented the case of a 60-year-old woman with a bilateral midfemoral
pain for 8 years[4]. In the case of Balkissoon and al, a 39-year-old
woman experienced intermittent severe pain in both lower legs for
several years[5].
These data suggest that this condition is more common in women than in
men unlike our case.
No similar musculoskeletal illness was found in any patient’s family
history. None of these patients have a history of trauma or infection.
No abnormal laboratory results including inflammatory reaction were
observed [2,3,4], such in our case.
The diagnosis of intramedullary osteosclerosis was retained after the
exclusion of disorders related to osteosclerosis, including
osteosarcoma, lymphoma, metastasis, stress fractures, metabolic
disorders and other sclerosing bone dysplasia [1,5]. Metabolic
disorders such as renal osteodystrophy, hypervitaminosis A and
pseudohypoparathyroidism need to be considered. Generalized
osteosclerosis is more characteristic of renal osteodystrophy and
pseudohypoparathyroidism. Hypervitaminosis A may lead to a periosteal
bone formation. Normal laboratory findings and clinical features can
eliminate these causes [3,9]. Only two known conditions,
Camurati-Engelmann disease and Ribbing disease are presented with
radiological and scintigraphic peculiarities similar to those of
osteosclerosis intramedullary. But, they can easily be dismissed since
the two are hereditary: (Engelmann: autosomal dominant, Ribbing:
autosomal recessive)[10,11].
Radiographs revealed, in the case of Vasilios and al, diffuse bilateral
asymmetric diaphyseal sclerosis of femoral bones, predominantly
endosteal, more extensive on the left side, with mild expansion and
cortical thickening of the affected segments. No periosteal reaction was
seen [4]. In the case of Balkissoon and al, The radiographs
demonstrated bilateral asymmetric mid-tibial and minimal fibular shaft
endosteal cortical scleroses. There was no substantial soft-tissue
abnormality [5]. In the cohort of Kullanuch Chanchairujira and al,
16 bone lesions were identified. All were located in lower extremities.
Both lower extremities were involved in the majority of patients. A
single extremity was involved in two patients. Cortical thickening was
seen in 10 bones and soft-tissue swelling was seen in eight lesions. No
periosteal reaction was seen [3]. Radiographs of the legs showed
bilateral hyperostosis involving the mid-third of the tibias in the case
of Rosenberg and al[6] and diffuse diaphyseal sclerosis of the femur
with widening of bone and endosteal hyperostosis in the case of Puranik
and al[7] .The clinical and radiographic findings in our patient
supported those studies.
Computed tomography (CT) scans showed, in these series intramedullary
sclerosis and soft-tissue swelling adjacent to the cortex. The cortex
was intact but thickened [2,3,4,8]. In the case of Balkissoon and
al, CT scan proofs were not available such as in our case [5].
Concerning MRI findings, MR images showed a low signal intensity on
images obtained with all pulse sequences, minimal increased signal
intensity was seen on T2-weighted images. Gadolinium-enhanced
T1-weighted fat-saturated images were obtained, and the images revealed
minimal enhancement in the lesions or surrounding soft tissue
[2,3,4]. In our case, MRI findings were not available.
Skeletal scintigraphy was performed in five patients with nine lesions
in the series of Chanchairujira and al. It showed intense tracer uptake
corresponding to the abnormalities seen on conventional radiographs
[3,4,6]. In one patient with bilateral lesions, an asymptomatic
lesion was incidentally found in an area that appeared normal at
conventional radiography [3]. Abe K and al and Puranik and al found
that whole body 99mTc-methylene diphosphonate (MDP) bone scan showed
abnormal tracer uptake with intense sclerosis in the intramedullary
region. Moreover, triphasic bone scan was performed : the initial
vascular phase and blood pool images at 2 min (phase 2) showed no
evidence of increased vascularity or soft tissue tracer pooling. Delayed
bone images (phase 3) showed a fusiform-shaped intense area of tracer
uptake in the diaphysis [2,7]. In our setting, scintigraphy was not
performed.
Open biopsy was carried out and histologic findings were available in
the series of Chanchairujira and al, but were non specific. The
peripheral and major part of the lesion was characterized by the
replacement of normal spongiosa by markedly sclerotic trabeculae and
were seen radiographically as osteosclerosis. There were some areas of
osteoblastic rimming of the trabeculae. Centrally, cell proliferation
associated with immature collagen deposition was noted [3]. In the
cases of Abe K and al, the histology showed trabecular bone sclerosis
with hypocellular fibrous tissue. The culture was negative[2].
Culture was sterile in the case of Vasilios and al. Pathologic
examination revealed a replacement of normal spongiosa by markedly
sclerotic and thickened trabeculae, obviously, seen radiographically as
osteosclerosis, in the case of Puranik too [4,7].
The management of intramedullary osteosclerosis is not well described in
the literature and is not yet standardized.
NSAID seem to be effective in this disease. Indeed, in our case, the
patient improved after prescription of diclofenac and he was relieved in
the followup. In the case of Skiadas and al, the patient also showed
improvement following NSAID therapy administered for one month [4].
In the series of Abe and al, pain was uncontrolled
by even opioid use[2]. In our case, the association of NSAID and
level 2 analgesic was sufficient.
Open surgical biopsy seems to be also an efficient treatment of IMOS. In
fact, besides the diagnosis confirmation, this technique allowed
medullary decompression. In the Kensaku and al series, open biopsy was
able to reduce the intensity pain, which is controlled afterwards only
by NSAID [2].
Although ,there were limitations to our study, such as the lack of CT,
MRI, scintigraphy and histologic results, we believe that our study and
our review of the literature can add data to this still unknown disease.