Fibromatosis colli

Fibromatosis colli
Other namesSternocleidomastoid tumor of infancy, Pseudotumor of infancy, infancy sternocleidomastoid pseudotumor
SpecialtyPediatrics, Pathology
SymptomsMass in the sternocleidomastoid muscle
ComplicationsTorticollis
Usual onsetcongenital
TypesBenign tumor
CausesUnknown
PrognosisGood

Fibromatosis colli (FMC), also termed sternocleidomastoid tumor of infancy, pseudotumor of infancy,[1] and infancy sternocleidomastoid pseudotumor,[2] is an uncommon (incidence: 0.4%–1.3% of live births), congenital tumor in one of the two sternocleidomastoid neck muscles although rare cases have presented with a FMC tumor in both sternocleidomastoid muscles.[3] A tumor is here defined as a growth of tissue that is not coordinated with the normal surrounding tissue and persists in growing even if the original trigger for its growth is removed. FMC tumors are benign growths that may cause disfigurements but are not cancers and do not metastasize (i.e. spread) to distant tissues.[2]

As judged by microscopic cytology analyses, fibromatosis colli tumors consist of spindle-shaped fibroblasts (i.e. the most common cell type in connective tissue) located in a background of collagen fibers, decomposing skeletal muscle fibers,[1] and, in some cases, regenerating skeletal muscle fibers.[4] The fibroblasts have a completely normal appearance with no evidence suggesting that they are malignant.[1] The World Health Organization in 2020 classified fibromatosis colli in the category of benign fibroblastic and myofibroblastic tumors.[5]

In the majority of cases, FMC tumors decrease in size and completely resolve by the newborn's second year. If left untreated, however, a significant percentage of cases progress to, and are the most frequent cause of, congenital muscular torticollis, i.e. an abnormal, asymmetrical head or neck position commonly called wry neck.[1] Untreated FMC tumors may also progress to facial asymmetry, plagiocephaly (i.e. flattened head), permanent loss of neck mobility, scoliosis (i.e. sidewise curvature of the spine), or other structural disfigurements that result from compensatory mechanisms.[6]

  1. ^ a b c d Lowry KC, Estroff JA, Rahbar R (September 2010). "The presentation and management of fibromatosis colli". Ear, Nose, & Throat Journal. 89 (9): E4–8. doi:10.1177/014556131008900902. PMID 20859860.
  2. ^ a b Alrashidi N (January 2021). "Fibromatosis colli or pseudotumour of sternocleidomastoid muscle, a rare infantile neck swelling". Brazilian Journal of Otorhinolaryngology. 88 (3): 481–483. doi:10.1016/j.bjorl.2020.12.003. ISSN 1808-8694. PMC 9422689. PMID 33441275.
  3. ^ Durnford L, Patel MS, Khamar R, Khurram R (April 2021). "Bilateral sternocleidomastoid pseudotumors-a case report and literature review". Radiology Case Reports. 16 (4): 964–967. doi:10.1016/j.radcr.2021.02.001. PMC 7897923. PMID 33664922.
  4. ^ Kaur N, Zaheer S, Kolte SS, Sangwan S, Ranga S (April 2021). "Sternocleidomastoid tumor of infancy-Importance of cytopathological diagnosis and challenges". Diagnostic Cytopathology. 49 (4): 533–539. doi:10.1002/dc.24687. PMID 33369154. S2CID 229690528.
  5. ^ Sbaraglia M, Bellan E, Dei Tos AP (April 2021). "The 2020 WHO Classification of Soft Tissue Tumours: news and perspectives". Pathologica. 113 (2): 70–84. doi:10.32074/1591-951X-213. PMC 8167394. PMID 33179614.
  6. ^ Skelton E, Howlett D (October 2014). "Fibromatosis colli: the sternocleidomastoid pseudotumour of infancy". Journal of Paediatrics and Child Health. 50 (10): 833–5. doi:10.1111/jpc.12506. PMID 24548127. S2CID 40754084.