Immunohistochemistry in surgical pathology practice: a current perspective of a simple, powerful, yet complex, tool.

Immunohistochemistry (IHC) is a powerful tool in the surgical pathologists' armamentarium. The requests for IHC and the list of monoclonal antibodies have increased tremendously in the past decade. Issues concerning technical reproducibility, uniformity of interpretation, inter-laboratory comparability, and quality assurance are assuming greater importance due to the increased availability of IHC and its impact on diagnosis and therapy. An attempt has been made to give a current perspective of this simple and yet, in some aspects, a complex tool.

Epithelioid sarcoma of the foot with subsequent lesion in hand: metastatic lesion or second primary?

Epithelioid sarcomas (ES) are rare tumors of soft tissue that have a propensity to occur in the extremities. Epithelioid sarcomas are known to metastatise to draining lymph nodes and commonly to the lungs. Herein, a case of epithelioid sarcoma which recurred in an unusual site namely the distal phalanx of left middle finger, six months post amputation of the primary lesion in the left foot is being reported. The ipsilateral inguinal lymph node showed metastatic deposits. The tumor at both these sites had similar histology and an identical immunohistochemical (IHC) pattern showing reactivity to cytokeratin (CK), epithelial membrane antigen (EMA), vimentin (Vim) and CD34. This case is presented to record an unusual occurrence of ES in the distal phalanx of middle finger with an ES of foot. The metastasis of ES to the distal acral bones has not been documented till date.

Anaplastic large cell lymphoma (ALCL) presenting as primary bone and soft tissue sarcoma--a study of 12 cases.

This study highlights the rare presentation of anaplastic large cell lymphoma as primary bone and soft tissue tumour. Twelve cases were studied. Clinical impression was non Hodgkin's lymphoma in 4 cases, sarcoma in 6 (osteosarcoma-2, Ewing's/primitive neuroectodermal tumour-1, and sarcoma NOS-3), and tuberculosis of thoracic spine in 1 and the last case involving the rib had a differential diagnosis of tuberculosis and NHL. Histology revealed round cells with eosinophilic cytoplasm and pleomorphic nuclei. Immunohistochemically all tumours were CD30 positive and 8 of 9 cases (88.9%) showed ALK-1 positivity. The pleomorphic cytomorphology ofALCL leads to confusion with the more frequent bone and soft tissue sarcomas affecting the musculoskeletal system. A high index of suspicion is necessary to initiate the correct panel of immunohistochemical markers to first confirm the lymphomatous nature of this tumour and to subsequently subclassify. This alone will lead to an accurate recognition of ALCL and the appropriate chemotherapy.