Showing most revelant items. Click here or hit Enter for more.
Leiomyosarcoma
Lesions restricted to cutis only rarely metastasize
Microscopic
• Perpendicularly oriented fascicles of spindle cells
• Brightly eosinophilic cytoplasm
• Blunt-ended nuclei
• Nuclear atypia and mitoses
Ancillary Tests
• Labels as per smooth muscle: Desmin, actin, calponin, caldesmon
Some cases stain with keratins
Top Differential Diagnoses
• Sarcomatoid squamous cell carcinoma
• Atypical fibroxanthoma
• Leiomyoma
• Dermatofibroma/fibrous histiocytoma
• Nodular fasciitis
• Inflammatory myofibroblastic tumor
Cutaneous Leiomyosarcoma (Atypical Smooth Muscle Tumor)Based on the lack of involvement of the subcutaneous adipose tissue, a favorable prognosis would be anticipated for this lesion. In fact, some observers have suggested diagnosing such superficial cutaneous lesions as atypical smooth muscle tumors.
Superficial Area of Cutaneous LeiomyosarcomaThis leiomyosarcoma (LMS) extended into the subcutis. It is composed of perpendicularly oriented fascicles of brightly eosinophilic cells. Even at scanning magnification, atypical nuclei stand out .
Leiomyosarcoma at High MagnificationMitotic figures are usually easily found in LMS. There is no need to search for numerous mitoses, although mitotic counts assist in assigning a sarcoma grade. Note the bright pink color of the tumor cells’ cytoplasm.
Leiomyosarcoma With Anaphase BridgeLMSs do not show a characteristic translocation and have chromosome instability, as indicated by the presence of anaphase bridges , long cords of chromatin that remain as cells separate in anaphase. Note the blunt-ended nuclei .
TERMINOLOGY
Abbreviations
• Leiomyosarcoma (LMS)
Definitions
• Malignant neoplasm composed of cells exhibiting smooth muscle differentiation
Most common overall sarcoma type if uterine and visceral examples are included
• Age
Middle-aged adults
• Sex
No gender preference overall
Presentation
• Cutaneous LMS presents as single nodule or plaque-like tumor
May be ulcerated or show serum crusting/hemorrhage
• Deep soft tissue tumors present as mass, often asymptomatic, in extremities
Retroperitoneum most common site
Vena cava examples often symptomatic
• Uterine examples considered separately with unique diagnostic criteria
Treatment
• Surgical excision
Radiation
Chemotherapy for metastatic tumors
Prognosis
• Outcome site and stage dependent as with other sarcoma types
Lesions restricted to cutis only rarely metastasize
– Some observers have advocated diagnosing them as atypical SMTs
Subcutaneous lesions
– Up to 40% of tumors metastasize
– Over 30% of patients with subcutaneous tumors die of disease
Retroperitoneum: About 80% of patients die of disease, typically with metastases
Bone: Metastases in up to 1/2 of patients
Vena cava: 5- and 10-yr survival 50% and 30%, respectively
Head and neck: Over 1/2 metastasize
MICROSCOPIC
Histologic Features
• Perpendicularly oriented fascicles of spindle cells
• Cells show brightly eosinophilic cytoplasm
• Blunt-ended nuclei with nuclear atypia
• Some examples are epithelioid-appearing
• Any number of mitoses sufficient in subcutis, scrotal lesions, or deep soft tissue if nuclear atypia is present
• In vulva, some observers offered > 5 mitosis per 10 HPF as cutoff, but recurrences reported in lesions with any mitotic activity
Predominant Pattern/Injury Type
• Fascicular
Predominant Cell/Compartment Type
• Mesenchymal, smooth muscle
Variant and Special Forms
• Epithelioid leiomyosarcoma
Literature confounded because many epithelioid gastrointestinal stromal tumors (GIST) were termed epithelioid LMS in past
Found anywhere in body
Distinct epithelioid morphology, but more nuclear atypia than GISTs
Older studies reported smooth muscle actin (SMA) and muscle specific actin (MSA)-positive, desmin-negative immunophenotype, but desmin labels most lesions using modern methods
– Possible reflection of misdiagnosed GISTs
– Less sensitive desmin antibodies used in past
• Myxoid leiomyosarcoma
Grossly gelatinous
Extensive myxoid change, but zones of typical leiomyosarcoma allow for diagnosis
– Express desmin and actin
Only gold members can continue reading. Log In or Register to continue
.
, long cords of chromatin that remain as cells separate in anaphase. Note the blunt-ended nuclei 
.
Literature confounded because many epithelioid gastrointestinal stromal tumors (GIST) were termed epithelioid LMS in past
Extensive myxoid change, but zones of typical leiomyosarcoma allow for diagnosis
