History: Swelling right upper arm increasing in size since 5 months of age, painless swelling. Transillumination negative. Perop multilocular swelling with evidence of blood in cavities. Gross: Specimen container is labeled with the patient s name and medical record number and unmarked for site. Received in formalin is a single skin covered tissue piece measures 4.0 cm x 3.0 cm x 2.0 cm. The overlying skin measures 3.0 cm x 1.0 cm. Serial sectioning reveals multiple cystically dilated spaces below the skin. Representative sections are taken and submitted in blocks (A-C). Micro: Sections reveal skin with underlying tissue showing cystically dilated, variably shaped vascular spaces filled with proteinaceous material. Surrounding stroma shows inflammatory infiltrate and fibrosis. Diagnosis: RIGHT UPPER ARM, BIOPSY: Lymphangioma. No evidence of malignancy.