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case_images: Dermatomyositis diagnosis. (A) Skin biopsy: The skin biopsy revealed marked hyperkeratosis with focal keratosis, thinning of the epidermis, increased pigment in the basal layer, dilation of superficial dermal blood vessels, a limited presence of lymphocytes in the vicinity, sporadic pigmented cells, and slight mucin deposition observed between the collagen fibers in the dermis (positive Acinlan staining), which did not exclude the possibility of dermatomyositis. (B) Muscle biopsy: In the muscle biopsy, there were evident signs of partial degeneration in striated muscle tissue, loss of transverse lines, and a minor infiltration of lymphocytes between muscle fibers.
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case_images: Muscle biopsy results demonstrated partial degeneration of striated muscle, loss of transverse lines, and a minor lymphocyte infiltration between muscle fibers, thus firmly establishing the diagnosis of dermatomyositis ( Figure 1 ).
case_images: Small cell lung cancer diagnosis. The diagnosis of Immunohistochemistry: CK (AE1/AE3) (+) TTF-1(+) P40(-) CgA (+)  Syn (+)  CD56 (+)  INSM1 (+)  Ki67 (positivity rate 80%)  P53 (+)  Rb (-)  LCA (-)  CK7 (A small amount of +).
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case_images: To conclusively establish the nature of the lesion, a bronchoscopic biopsy was performed, confirming the diagnosis of small cell lung cancer (limited-stage, T1cN3M0 IIIB) ( Figure 2 ).
case_images: Therapeutic outcomes in small cell lung cancer (SCLC) and dermatomyositis.
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case_images: Moreover, the oral hormone dosage was further reduced to 5mg of prednisone ( Figures 3 ,  4 ).
case_images: Creatine kinase changes and hormone dosage.
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case_images: Moreover, the oral hormone dosage was further reduced to 5mg of prednisone ( Figures 3 ,  4 ).