PMC9336559_01
MRI and histopathological findings. (A) A gadolinium-enhanced fat-suppressed T1-wedged MRI of the thigh shows that the fascia of the gracilis and hamstring muscles is enhanced with high signal intensity (white arrowheads). (B, C) Short inversion time recovery image of the bilateral upper arms (B: right upper arm; C: left upper arm) shows areas of high signal intensity in the fascia of biceps and triceps brachii muscles (white arrowheads). (D) Haematoxylin- and Eosin-stained left triceps branchii muscle tissues show mild-to-moderate mononuclear cell infiltration around small vessels in the connective tissue between the deep fascia and muscles (yellow arrows). (E) Muscle fibres were almost intact in the same section as panel D (original magnification x100 in panels D and E). (F) Substance P-immunoreactive fibres (brown; yellow arrowheads) were innervated around small vessels in subcutaneous tissues adjacent to the deep fascia. (G) A few substance P-immunoreactive fibres (yellow arrowheads) were present around small arteries in connective tissue between the fasciculus in the same section as panel F (original magnification x200 in panels F and G).
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A gadolinium-enhanced fat-suppressed T1-wedged MRI of the thigh showed that the fascia of the gracilis and hamstring muscles was enhanced with high signal intensity (Fig. 1A). Short inversion time recovery image of the bilateral upper arms showed areas of high signal intensity in fascia of the biceps and triceps brachii muscles (Fig. 1B, C). En bloc biopsies of skin to the left biceps brachii showed almost intact muscle fibres (Fig. 1E) and mild-to-moderate mononuclear cell infiltration around small vessels in the connective tissue between the deep fascia and muscles (Fig. 1D). In this case, substance P-immunoreactive fibres were present around small vessels in subcutaneous tissue adjacent to the deep fascia (Fig. 1F) and around small arteries in connective tissue between the fasciculus (Fig. 1G), but not in muscle fibres.