PMC6779781_01
Clinical photograph showing a mass of left thigh without rash.
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F1
A 49-year-old male presented with a 9-month history of multiple anatomical site pain, a localized mass, and swelling of thighs (Figure 1) and calves, which gradually increased in size and quantity without systemic symptoms, such as fever, poor appetite, malaise, weight loss, or perspiration during sleep or after strenuous exercise.
Magnetic resonance imaging of calf and thigh masses. (A) A coronal T2-weighted image shows a mass with a clear boundary, with a long T2 signal and a short T2 signal at the center of the mass in the calf. (B) A coronal T2-weighted image shows muscular enlargement with increasing signal intensity over the muscles and subcutaneous areas in the thigh. (C) The axial T2-weighted image showed a clear boundary mass with a long T2 signal and a short or equal T2 signal at the center of mass in the gastrocnemius and soleus muscle. (D) The axial T2-weighted image shows a mass with a blurry boundary, with a long T2 signal and a short T2 signal at the center of mass in the lateral femoral muscle and adductor muscle.
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F2
Musculoskeletal MRI (Figure 2) examination showed diffuse abnormal signals on the bilateral calf and thigh muscles, suggesting infectious lesions or myopathy.
Histopathological examination of a mass and the nearby muscles. (A) Skeletal muscle HE staining, arrows indicate several well-formed inflammatory granulomas embedded among the muscle fibers (x50). (B) Skeletal muscle HE staining, arrows indicate inflammatory cell infiltration among the muscle fibers (x100). (C) Inflammatory granulomas embedded among the muscle fibers, red arrows indicate Langerhans cell, black arrows indicate epithelioid cells, and yellow arrows indicate lymphocytes (x400). (D) Inflammatory granulomas of the intramuscular mass (HE staining, x100).
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F3
Moreover, inflammation granulomas (including Langerhans cells, epithelioid cells, and lymphocytes) were visible under the microscope (Figure 3), and CD4(+), CD8(-), MHC-I(+), C5b-9(+) (Figure 4), and acid-fast stain(-) results were observed.
Immunohistochemical examination of the muscle near the mass. (A) Anti-CD4+ T cell monoclonal antibody immunohistochemical staining, positive expression of CD4+ in a large number of inflammatory cells (x100). (B) Anti-CD8+ T cell monoclonal antibody immunohistochemical staining, negative expression of CD8+ in the inflammatory cell (x100). (C) Anti-MHC-I monoclonal antibody immunohistochemical staining, MHC-I present on the sarcolemma (x200). (D) C5b-9 observed on the vessels (x200).
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F4
Moreover, inflammation granulomas (including Langerhans cells, epithelioid cells, and lymphocytes) were visible under the microscope (Figure 3), and CD4(+), CD8(-), MHC-I(+), C5b-9(+) (Figure 4), and acid-fast stain(-) results were observed.