low-grade myofibroblastic sarcoma

Definition : Low-grade myofibroblastic sarcoma is an uncommon tumour with a predilection for the head and neck region.

Low-grade myofibroblastic sarcoma (LGMS) represents an atypical tumor composed of myofibroblasts with a predilection for the head and neck, especially in the tongue and oral cavity, with a high tendency to local recurrence and metastasis, even after a long period. LGMS arising from maxillary sinus and buccal mucosa are not very common.

It bears morphological similarities to desmoid fibromatosis, except for its generally greater cellularity and focal but undoubted nuclear atypia.

Differential diagnosis

  fibromatoses : minimal nuclear atypia, usually negative for myogenic markers (but may sometimes express them focally)

 fibrosarcomas : may have focal (not diffuse) myofibroblastic differentiation; "herringbone" fascicular pattern, a diagnosis of exclusion (Histopathology 2006;49:152) that should be made with much hesitation

 inflammatory myofibroblastic tumor: tumor of myofibroblasts with prominent lymphoplasmacytic infiltrate scattered amongst tumor cells, usually less atypia than myofibroblastic sarcoma, often ALK+ (Hum Pathol 2008;39:846)

- leiomyosarcoma: alternating fascicular pattern, more eosinophilic cytoplasm, more strong and diffuse staining for myogenic makers, usually dense cytoplasmic actin staining rather than "tram track" pattern

-myofibroma / myofibromatosis: often multiple and often in children (although solitary lesions and lesions in adults are both common as well), usually zonated with peripheral myoid nodules with intervening central cellular spindle areas with ectatic "hemangiopericytic" vessels; more diffuse or atypical forms of myofibroma may be very difficult to distinguish from myofibroblastic sarcoma (zonation is helpful feature)

 nodular fasciitis: not infiltrative, not deep, @<@ 3 cm usually, lacks chromosomal anomalies seen in myofibroblastic sarcoma (although recently a recurrent translocation resulting in MYH9-USP6 gene fusion has been described in many cases of nodular fasciitis (Lab Invest 2011;91:1427)

 solitary fibrous tumor (SFT): diffusely positive for CD34, usually "patternless" haphazard arrangement of cells, usually no atypia (except in malignant SFT)

Open references

 Low-grade myofibroblastic sarcoma of maxillary sinus and buccal mucosa: Two rare cases and review of the literature. Ghosh A, Bandopadhyay A, Sarkar R. Indian J Pathol Microbiol. 2019 Jan-Mar;62(1):119-121. doi : 10.4103/IJPM.IJPM_99_18 PMID: 30706874 Free Article

Paywall References

 Nagata Y, Matsuno T, Hamada N, Shimose S, Arihiro K, Ochi M. Low-grade myofibroblastic sarcoma of the palm. Scand J Plast Reconstr Surg Hand Surg. 2008;42(3):164-7. PMID: 18470796

 Koga S, Ikeda S, Urata J, Chijiwa R, Abe K, Hayashi T, Eishi K, Kohno S.Primary high-grade myofibroblastic sarcoma arising from the pericardium. Circ J. 2008 Feb;72(2):337-9.PMID: 18219177

 Eisenstat J, Gilson T, Reimann J, Sampson B. Low-grade myofibroblastic sarcoma of the heart causing sudden death. Cardiovasc Pathol. 2008 Jan-Feb;17(1):55-9. PMID: 18160061

 Jay A, Piper K, Farthing PM, Carter J, Diwakar A. Low-grade myofibroblastic sarcoma of the tongue. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007 Nov;104(5):e52-8. PMID: 17964473