Figure 1. Swelling with overlying erythema on the anterior aspect of the left upper arm.
Figure 2. Computed tomographic scan of the upper limbs showing a tumor arising from the left biceps muscle.
Figure 3. Cohesive sheets of large pleomorphic cells displaying vesicular nuclei with peripheral condensation of chromatin are seen in the dermis. Some have prominent irregular nucleoli and amphophilic or vacuolated abundant cytoplasm. Several mitotic figures are also noted (hematoxylin-eosin, original magnification ×400).
Figure 4. Lymphoma cells display strong staining of cell membranes for Ki-1 antigen CD30 (Bcr-H2 monoclonal antibody, peroxidase-antiperoxidase, original magnification ×400).
The CT scan of the thigh showed a tumor arising from the left rectus femoris muscle. Examination of the bone marrow and cerebrospinal fluid did not show any metastases. The lymphoma was classified as stage 3 (Murphy classification), and the child was treated with chemotherapy using the French LMB-89 protocol. She has completed therapy and is currently healthy with resolution of all the swellings.
Large cell lymphomas constitute approximately 20% of all childhood non-Hodgkin lymphomas.1 Ki-1–positive anaplastic large cell lymphoma (Ki-l+ ALCL) is a tumor that expresses the antigen CD30, which is detected by the monoclonal antibody Ki-1. It is associated with the translocation t(2;5).2 Seventy percent of ALCL are of T-cell lineage, as in this case.3 The usual presentation of Ki-1+ ALCL is lymphadenopathy. Common extranodal sites include skin, soft tissue, lung, and bone. Bone marrow and central nervous system involvement is uncommon.4
Primary skeletal muscle lymphoma is rare. In a large retrospective series, only 8 (0.1%) of 7000 cases had primary muscle lymphoma, with the thigh and upper arm being the most common sites of involvement.5 Previous reports in the literature have been mainly in adults, particularly the elderly population.6
In children with advanced-stage ALCL, CD30 positivity is associated with a better survival than CD30 negativity.7 Overall survival rates for children with Ki-1+ ALCL treated with chemotherapy are approximately 70% to 80%, regardless of whether a B-cell or T-cell protocol is used.8 Our patient responded well to a protocol for B-cell lymphomas.
Accepted for publication November 24, 1999.
Reprints: Bina S. Menon, MRCP (UK), No. 53, Lorong 5/4 H, 46000 Petaling Jaya, Selangor, Malaysia.
Pathological Case of the Month. Arch Pediatr Adolesc Med. 2001;155(3):412. doi:10.1001/archpedi.155.3.411