CASE 11489 Published on 16.01.2014

Langerhans cell histiocytosis - an unusual adult long bone involvement case

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Santhosh Mauvva Venkatesh Reddy1, John H Miller2

Raigmore Hospital,
NHS Highlands, Radiology;
Inverness IV2 3UJ;
Email:sunnymvu99@yahoo.co.in
1MBBS, MRCP
2FRCP, FRCR
Patient

60 years, female

Categories
Area of Interest Bones ; Imaging Technique Conventional radiography, MR, Nuclear medicine conventional
Clinical History
A 60-year-old female patient presented with a 6-month history of right thigh pain. She was in remission following left hemicolectomy for Duke's B colonic carcinoma 2 years before.
Imaging Findings
Plain radiograph showed destructive lesion in distal right femur.

On MRI this 15 cm lesion demonstrated marked marrow infiltration, endosteal scalloping and cortical breakthrough with soft tissue extension. The knee articular surface was spared. Interestingly, a 4 cm long occult lesion was also visible in asymptomatic distal left femur of similar signal intensity and early endosteal scalloping suggestive of a synchronous lesion.

Technetium-99m whole body bone scintigraphy showed abnormal intense tracer uptake corresponding to lesions in bilateral femur with less intense uptake in the left femur. Asymmetrical tracer uptake was also noted in left mastoid region possibly related to area of previously treated LCH.

The patient was admitted to the Radiologist who had treated the left temporal bone Langerhans cell histiocytosis [LCH] 7 years before; important clue to diagnosis was not highlighted by the clinician.
Biopsy of the right femur lesion confirmed bone involvement by LCH but no metastatic carcinoma. The patient was selected for combination chemotherapy treatment.
Discussion
Langerhans cell histiocytosis (LCH) is primarily a rare childhood (0-15 years) disease with age at onset varying according to the variant of LCH. The pathogenesis of LCH is unknown with suggestions of a reactive or myeloid oncogenic process and evidence of a role for immune dysfunction. It involves clonal proliferation of histiocytes predominantly affecting the reticuloendothelial system of the bone marrow, liver, spleen, lymph node and lung.
Eosinophilic granuloma [EG] form of the LCH affects older children and young adults. It is characterised by skeletal lesions with polyostotic EG occurring 3 times less frequently than solitary bone involvement [1].
MRI findings in LCH of the bone are non-specific and highly variable correlating to the stage of the disease [2]. LCH has less extensive peritumoral oedema than in Ewing's sarcoma or osteomyelitis. Endosteal scalloping and a budding appearance with a periosteal reaction on CT and MRI may be helpful signs to radiologists for differentiation of LCH from malignant tumours in adults [3].
LCH can mimic infection and benign as well as malignant tumours on imaging. Therefore a biopsy is necessary to confirm a tentative diagnosis especially in the context of a known malignancy as in this case. This has obvious treatment and prognostic implications to the patient. The prognosis is more favourable for focal disease than multifocal disseminated disease of LCH, which involves organs other than the skeletal system. MRI is presently the most informative imaging tool in the management of bone LCH with role in staging, treatment and follow-up of bone LCH [4].
It is rare for LCH to occur in older patient as in this case and also unusual to affect the long bones as only one third of the lesions involves the long bones. The femur [13%] is most commonly involved [1]. Recognition of this is important for both clinicians and radiologists so as to be aware of and consider LCH in their differential diagnosis in an older adult age group. One has to be alert to the possibility of asymptomatic occult synchronous lesions as well. Whole body MRI is suggested to be more useful than conventional radiography and scintigraphy in not only locating more skeletal lesions, but in identifying extra-skeletal lesions also [5].
Differential Diagnosis List
Langerhans cell histiocytosis / Eosinophilic granuloma
Langerhans cell histiocytosis
Skeletal metastases
Lymphoma
Osteomyelitis
Ewing\'s/Osteo sarcoma
Final Diagnosis
Langerhans cell histiocytosis / Eosinophilic granuloma
Case information
URL: https://www.eurorad.org/case/11489
DOI: 10.1594/EURORAD/CASE.11489
ISSN: 1563-4086

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