The dot-in-circle sign is a recently described sign reflecting the unique pathological feature of mycetoma on MRI
Madura foot.
This condition can be caused by either filamentous actinobacteria (actinomycotic mycetoma) or true fungi (eumycotic mycetoma).
Gill,
who worked at a dispensary in the southern Indian province of Madura,
first recognized mycetomas as a disease entity in 1842.
Godfrey first documented a case of mycetoma in Madras,
India.
Native peoples of the province of Madura commonly called the disease Madura foot.
In 1860,
Carter,
who established the fungal etiology of this disorder,
first proposed the term mycetoma
n 1872,
Carter further proposed the terms melanoid and ochroid in an attempt to classify the disease into 2 varieties on the basis of the black or pale-colored granules (ie,
grains,
sclerotia) produced by the etiologic agents.
Pathophysiology:
The foot is the most common site of infection,
and 70% of all mycetomas affect the foot.
Other reported sites of involvement include the upper extremities,
trunk,
buttocks,
eyelids,
lacrimal glands,
paranasal sinuses,
mandible,
scalp,
neck,
perineum,
and testes.
The disease is initially limited to the skin and subcutaneous tissue but may eventually spread through the fascial planes to contiguous structures such as muscle,
bone,
blood and lymphatic vessels,
and nerves.
Rarely,
the disease may spread to the regional lymph nodes or viscera.