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RESIDENT
CASE
STUDIES
September 11,
2003: Case 1 Table
of Contents
| List
of Diagnoses | Case 1 | Case 2 |
Case
3 | Case 4
40 year old black female with a right foot
mass
Discussion by Karen Cline, DO
Clear cell sarcoma of soft tissue, also known as malignant melanoma of soft
parts, is a distinct entity and differs from conventional
melanoma in several ways. It is deeply situated and intimately associated
with tendons or aponeurosis. It lacks junctional change and rarely
involves the epidermis. It is associated with translocation of chromosomes
12 and 22, t(12;22)(q13;q12).
Distribution: Occurs in women more
than in men; young adults age 20-40 years
Gross Appearance: Well-circumscribed,
lobulated mass, 1-6cm, with a gray-white cut surface. There may or may not
be focal areas of hemorrhage or dark pigment. It is frequently attached to
tendons.
Microscopic
Appearance:
- The most distinguishing
feature is the pattern of compact nests or fascicles surrounded by
delicate fibrocollagenous tissue.
- The individual cells
have clear nuclei filled with glycogen, a round to oval vesicular
nuclei and a deeply basophillic nucleoli.
- It is occasionally
associated with wreath-like multinucleated giant cells with tumor cells at the
periphery.
- The mitotic rate is 2-3
per 10 high power fields.
Immunostains:
- S 100 positive, reticulin stain will
show the characteristic growth pattern. Some may stain aberrantly for
cytokeratin.
Differential Diagnosis:
- Fibrosarcoma: S100 negative, higher
mitotic rate, herringbone pattern
- Malignant peripheral nerve sheath tumor:
associated with large peripheral nerve, higher mitotic rate
- Spindle cell malignant melanoma;
involves dermis, associated with skin changes
- Cellular blue cell nevus: cells are
smaller with a pinpoint nucleoli
- Gastrointestinal stromal tumor
References:
- Enzinger
FM, Weiss SW, and Goldblum, JR. Weiss's Soft Tissue Tumors. St Louis:
Mosby Publishing; 1995.
- Stephen
S Sternberg et al. (Eds): Diagnostic surgical pathology, Volume 1, 3rd
edition. Lippincott William & Wilkins.
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