An Approach to Histopathological Reporting of Soft Tissue Tumour
pathologist should answer the following questions in a step-wise
manner before making the final diagnosis:
Is it a primary tumour?
Could it be an inflammatory process (Example: Pseudotumour or abscess) ?
Is it a metastatic tumour or involvement by lymphoma or leukaemia?
Is it a pure soft tissue tumour or a lesion like spindle cell carcinoma?
Does the tumour have any recognizable differentiation?
Is it benign, locally aggressive but non-metastasizing or malignant?
Is the excision complete with adequate margins?
Are there any other histological prognostic data present?
following clinical details should be provided by the clinician:
Location including anatomical planes (Cutanous, subcutaneous or deep)
Deep fascia - Sarcoma
Size and duration - Example: Sarcoma is larger with longer history.
Fasciitis is smaller and of recent onset.
Any history of pain or tenderness.
Whether single or multiple,
Whether underlying structures are involved,
Whether rapid or slow growing tumour.
The histopathology report should include the following features:
Spindle cell carcinoma can be ruled out by appropriate immunostains.
Soft tissue lymphoma must be considered in any large round cell tumour in soft tissue.
Criteria of malignancy depends on the cell type:
Smooth muscle tumour - Presence of mitoses or necrosis in deep lesions are consistent with malignancy.
Myofibroblastic tumours- pleomorphism, cytologic and mitotic atypia with large nucleoli and necrosis indicate malignancy.
Light microscopy is usually the only useful technique for distinguishing reactive lesions or benign tumours from malignant tumours.
Well differentiated liposarcoma may have areas resembling its benign counterpart.
Fibromatosis can be difficult to distinguish from low grade sarcoma.
PAS is positive-
-Granular cell tumour
-Epithelial mucin in biphasic synovial sarcoma.
-Glycogen in smooth and skeletal muscle tumour, chondroid tumours and liposarcoma
-Diastase resistant inclusions inalveolar soft part sarcoma.
Masson trichrome - Collagen and muscle
PTAH- Cross striations inrhabdomyosarcoma.
Reticulin- Demonstrate architecture and vascular pattern.
Following tumours may be under- diagnosed as a benign lesions :
This may be avoided by:
1. Careful assessement of architecture, cytological character, tumour stromal interphase and associated reaction ;
2. Immunohistochemical findings ;
3. Awareness of other diagnostic possibilities.
Following reactive soft
tissue lesion may be overdiagnosed as sarcomas:
Cytokeratin- (EMA and pancytokeratin) -Epithelial marker.
Desmin, smooth muscle actin display muscle differentiation.
CD31 and von Willebrand factor- vascular marker
LCA, B and T cells markers - Lymphoid Tumour Marker
S100 protein - Demonstrate neural, adipocytic, and cartilaginous differentiation.
CD99, neuron specific enolase, (NSE) and PGP 9.5- primitive neuroectodermal tumours/Ewing's sarcoma.
Myoglobin- Display skeletal muscle differentiation.
Tissue Tumour Online
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