Michelin tire baby syndrome
This disorder was first named in 1969 by Ross et al. after the French tire manufacturer Michelin. Since this description, fewer than 40 patients have been described in the literature.
The cause of MTBS is currently unknown; hypotheses include abnormal elastin production or subsequent derangements in transport by lesional fibroblasts, metaplasia of dermal structures, or overgrowth of subcutaneous structures that then become differentiated as fat or muscle cells. MTBS may instead be a distinct clinical feature that reflects multiple etiologies. MTBS is thought to be associated with nevus lipomatosus or generalized smooth muscle hamartoma, although pseudo-Darier sign (transient piloerection and induration induced by rubbing in smooth muscle hamartomas) is usually negative.
MTBS is thought to have autosomal dominant inheritance, although recent evidence may suggest an autosomal recessive nature instead. Chromosomal mosaicism, balanced paracentric inversion of chromosome 7, and deletion of chromosome 11 have been reported and may be causative factors.
D21.9 – Benign neoplasm of connective and other soft tissue, unspecified
239142006 – Michelin-tire baby
Differential Diagnosis & Pitfalls
- Generalized smooth muscle hamartoma or nevus lipomatosus on biopsy may present with MTBS phenotype.
- Ainhum – Spontaneous autoamputation of digits is uncommon in MTBS, and creases are usually symmetrical. Ainhum is limited to the fifth toe.
- Amniotic band syndrome – Usually unilateral, solitary, asymmetric, and not a multisystem disorder. Associated with craniofacial abnormalities. Often results in amputation or permanent disability.
- Beare-Stevenson cutis gyrate syndrome – Associated with dermatomegaly localized to the scalp, forehead, face, and neck.
- Cutis laxa – Folds represent cutaneous laxity instead of excess tissue as in MTBS.
- The skin folds may resemble cutis verticis gyrata; however, this disease is limited to the scalp.