Fibrodysplasia ossificance progressiva: A familial presentation.

Fibrodysplasia ossificans progressiva is a rare disorder progressing to ossification of tissues causing disability. We report a case of father and daughter in a family presenting with this condition. The diagnosis was made with X-rays. However, Technetium-99m Methylene Diphosphonate bone scan showed extensive extra-osseous localization of tracer suggesting ossification of multiple ligaments, tendons, muscles and connective tissue.

A 45-year-old man presented with deformities of fingers and toe since childhood and fixed flexion deformity of the pelvis after a fall 2 years back [Figure 1]. He had deformed, and shortened fingers and toes as shows in the Figure 1b. His X-ray of pelvis and femur region revealed linear calcification joining left ischeal tuberosity with the medial aspect of left femur that was the cause of his fixed flexion deformity of the pelvis. The 19-year-old daughter of the man also had fixed flexion deformity of right hip joint region. The neck flexion was impaired and complained of pain in the chest on deep inspiration. The X-ray of the hip region revealed ectopic calcification of the ligaments and muscles anterior to the right hip joint. The Technetium-99m Methylene Diphosphonate (Tc-99m MDP) bone scan is done in above two cases revealed the extent of extra-osseous calcification in detail as marked in Figures 1 and 2.

Figure 1

(a) Static planar images of technetium-99m methylene diphosphonate bone scan showed extra-osseous calcification in small joints of both hands (yellow arrow), psoas muscle bilaterally (black arrow), linear calcification joining left ischeal tuberosity and medial border of shaft of left femur (red arrow), insertion of sartorius muscle at upper tibia (white arrow). (b) Toe deformities. (c and d) Extra-osseous bone formation joining left ischeal tuberosity and medial border of shaft of femur (green arrow) on X-ray anterior-posterior and lateral views respectively

Figure 2

(a) Technetium-99m methylene diphosphonate bone scan showed ectopic calcification in various muscles: Left trapezius and scapular region (blue arrow), right pectoral (red arrow), ligaments and para-spinal muscles in dorsal and lumbar region (transparent arrow), intercostals and chest wall bilaterally (black arrow), bilateral psoas (green arrow), linear calcification joining right inferior superior iliac spine and greater trochanter (yellow arrow), inter-tarsal joints bilaterally (purple arrow) (b) X-ray of pelvis showing calcification between right inferior superior iliac spine and greater trochanter (yellow arrow)

The extra-osseous calcification is seen on Tc-99m MDP bone scan due various pathologies. Fibrodysplasia ossificans progressiva being one of the rare causes of connective tissue differentiation characterized by congenital malformation of the great toe and progressive heterotopic ossification of tendons, ligaments, fascia, and skeletal muscle.[1234] It shows autosomal dominant mode of inheritance; where bone morphogenic protein 4 is found to be over-expressed in lymphoblastoid cells in periosseous fibroproliferative lesion cells of these patients.[56789] Tc-99m MDP bone scintigraphy demonstrates heterotrophic ossification in the early stage and helps in the assessment of the extent and progression of the disease.[1011] Since curative therapy is not available; prevention of injuries, trauma and subsequently formation of ectopic ossification.[12]