Bone sarcoidosis

Clinical History

A young male patient presented with painful swollen hands.

Imaging Findings

The patient presented with a 3 years history of painful swollen hands. Clinically he had lupus pernio with ulcerated, red and inflamed external nares on right side. He had bilateral dactylitis with the fingers swollen, red and tender and there was a large ulcer on both the right and left index fingers. X-ray of both hands (Figure 1) followed by a Chest x-ray (figure 2) were taken. A follow up chest x-ray after 2 years showed pulmonary parenchyma changes and high resolution CT was obtained (figure 3).

Discussion

Sarcoidosis is a disease that exhibits extremely heterogeneous clinical manifestations. Although the lungs are the most commonly involved organs, the extension of the granulomatous process may also affect the bones. Almost any bone can be involved; curiously, the small bones of the hands and feet are most frequently affected. The nasal bones are involved particularly in patients with lupus pernio. Skull, vertebrae, pelvis, ribs, sternum, and the distal ends of long bones are rarely affected. The frequency of bone involvement varies from 3% to 13% [1].
Sarcoidosis bone lesions are characterized by their bilateral distribution; the site of origin (cortical, preservation of the periosteum); location (hands and feet); position (usually the ends of the affected bones); and the shape (cystic or lacelike with minimal disturbance in the nearby soft tissues). In advanced cases, as subchondral lesions extend into joint spaces, the adjacent joints may be involved. Calcification is absent. The questions regarding the cause and localization of bone lesions in sarcoidosis remains unanswered [2].
Although bone lesions are often asymptomatic, in many cases the affected part may be tender and painful. Stiffness of the digits, finger deformities, and soft tissue swelling overlying the bone cysts are frequent and often precede the radiologic diagnosis.
James and Williams [3] classified bone lesions into the following:
1.Lytic lesions: these lesions are either minute cortical defects in phalangeal heads or larger rounded punched out lesions involving cortex and medulla, most frequently of the middle and proximal phalanges. It likely reflects an osteoporotic process producing tunnelling that is more local and destructive. The peripheral lesions simulate marginal erosions.
2.Permeative lesions: "tunnelling" of the cortex of the shaft of the phalanx, followed by remodeling of the cortical and trabecular architecture, results in a reticular pattern. The concave phalangeal shafts become tubular. The lesions are usually accompanied by soft tissue swelling.
3.Destructive lesions: in an advanced sclerotic phase, the bone may develop multiple fractures of devitalized cortex resulting in a sequestrum. Joint destruction is localized to the subchondral areas of the bone.

As a rule, the recognition of typical punched-out lesions is relatively easy if the patient presents with multisystem features of sarcoidosis. However, diagnosis may be difficult if the bone lesion occurs in the absence of the typical pulmonary and extrapulmonary features of sarcoidosis. Many clinical disorders, including tuberculosis, histoplasmosis, coccidoidomycosis, leprosy, brucellosis, syphilis, Wegener granulomatosis, eosinophilic granuloma, multiple myeloma, lymphoma and metastasis [4] can cause bony lesions indistinguishable from those due to sarcoidosis. Nevertheless, in daily practice only a few diseases need to be differentiated from sarcoidosis as far as bone involvement is concerned. In difficult situations a bone biopsy is needed to demonstrate the presence of noncaseating granuloma and exclude other conditions by appropriate laboratory tests and cultures.

Osseous sarcoidosis responds poorly to corticosteroids as well as to other drugs used in treating the illness [5]. Corticosteroids often decrease pain and ameliorate soft tissue swelling but do not completely normalize the bone abnormality. Symptomatic relief may be obtained by nonsteroidal anti-inflammatory agents.

Differential Diagnosis List

Final Diagnosis

Sarcoidosis

URL:	https://www.eurorad.org/case/2265
DOI:	10.1594/EURORAD/CASE.2265
ISSN:	1563-4086