Simple bone cyst

Case contributed by MD Gaspar Alberto


Non-specific knee pain

Patient Data

Age: 25
Gender: Male

SOLITARY LYTIC BONE LESION: When you see lytic bone lesion think of FOGMACHINE.

Differential Diagnosis (Mnemonic = FOGMACHINES)

F = Fibrous Dysplasia

O = Osteoblastoma

G = Giant Cell Tumor

M = Metastasis / Myeloma

A = Aneurysmal Bone Cyst

C = Chondroblastoma

H = Hyperparathyroidism(brown tumors)/ Hemangioma

I = Infection

N = Non-ossifying Fibroma

E = Eosinophilic Granuloma / Enchondroma

S = Solitary Bone Cyst


Wise Sayings About Solitary Lucent Lesions.1. With a long lesion in a long bone, think of fibrous dysplasia.

2. Simple cyst, enchondroma, and fibrous dysplasia can mimic each other and can be hard to distinguish. Thus, when you think of one of these three entities, also think of the other two.

3. Giant cell tumors nearly always occur near a joint surface.

4. For lucent lesions in patella, calcaneum, and most apophyses, one should include the classic epiphyseal entities such as chondroblastoma, giant cell tumors and aneurysmal bone cys


Case Discussion

SIMPLE BONE CYST: A unicameral (simple) bone cyst is a cavity found within a bone that is filled with straw-colored fluid. It is a benign (non-cancerous) condition.

Unicameral bone cysts (UBC) are usually found in patients younger than 20 years of age. Unicameral bone cysts occur in one bone, in one location. The location of the cysts tends to be in the upper arm (proximal humerus) or thighbone (proximal femur). Less common locations include the pelvis, ankle (talus), or heel (calcaneus).

There is no known cause. Little is known about the development of unicameral bone cysts. There are theories involving a growth defect or disturbance at the epiphyseal plate leading to the formation of a unicameral bone cyst. However, this is not completely understood. No preventive measures can be recommended.

Most unicameral bone cysts have no symptoms. Some are discovered incidentally. Other unicameral bone cysts are not noticed at all.

If a unicameral bone cyst is thinning the bone, there may be pain with weightbearing activities. If there is a pathologic fracture through the cyst, the affected arm or leg may have pain, swelling, and deformity

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Case information

rID: 14828
Published: 30th Aug 2011
Last edited: 12th Jan 2016
Inclusion in quiz mode: Excluded

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