Dermatomyositis, clinically presenting with cutaneous ulcers, with histopathologic evidence of perforating collagenosis.

Dermatomyositis is a systemic, autoimmune diseasewith a variety of clinical features that often includemyositis and characteristic cutaneous findings. Asubset of patients with dermatomyositis developcutaneous ulcers, often in the setting of vasculitis orvasculopathy. We present a case of dermatomyositiswith cutaneous ulcers that show perforatingcollagenosis on histopathologic examination.Acquired reactive perforating collagenosistypically occurs in the setting of diabetes mellitus,chronic renal failure, and other pruritic conditions,and this case represents a rare association withdermatomyositis, which may ultimately be helpful inelucidating the pathophysiology of this perforatingdisorder.

Non-Hodgkin Lymphoma with Synovial Involvement of the Knee.

Musculoskeletal involvement occurs in approximately 25% of patients diagnosed with non-Hodgkin lymphoma (NHL). Skeletal involvement is typically secondary, with primary lymphoma of the bone being much rarer. We describe a case in which a 52-year-old man initially presented features suggestive of Lyme arthritis in his left knee. A synovial biopsy performed as part of a synovectomy procedure revealed a proliferative synovium with dense lymphoplasmacytic B cell infiltrate, suggestive of NHL. An inguinal lymph node biopsy was also performed but did not produce results pathologically similar to those of the left knee synovial biopsy.