Michelin-tire baby syndrome resulting from diffuse smooth muscle hamartoma

Post-zygotic ACTB mutations underlie congenital smooth muscle hamartomas

BACKGROUND

Congenital smooth muscle hamartomas (CSMHs) are benign lesions that share clinical and histopathological features with Becker nevus, a mosaic disorder associated with post-zygotic ACTB mutations. Given the clinical and histopathological overlap between CSMH and Becker nevus, we hypothesized that post-zygotic mutations in ACTB may underlie CSMH.

METHODS

Direct sequencing of ACTB gene in affected and unaffected tissue isolated from one case of hemihypertrichosis and hemihypertrophy corresponding to giant segmental CSMH and hemihypertrophy. This was followed by direct sequencing with and without enrichment assay for hotspot ACTB mutations in affected tissue from 12 samples of isolated CSMH from unrelated individuals.

RESULTS

In total we identified somatic missense ACTB mutations in 9 out of 13 CSMHs (69%). Mutations were either novel or previously reported in Becker nevi and Becker nevus syndrome.

CONCLUSIONS

CSMHs result from post-zygotic ACTB mutations. This study proves that CSMHs and Becker nevi are nosologically related, and expand the phenotypic spectrum of ACTB mutations.

Cutaneous Smooth Muscle Tumors: A Review

Smooth muscle tumors occur infrequently in the skin. They consist of a diverse group of lesions representing hamartomas as well as benign and malignant neoplasms. They may arise from arrector pili muscle, specialized smooth muscle of the genitalia, or vascular smooth muscle. Although rare, accurate diagnosis and classification of cutaneous smooth muscle proliferations is important as they can exhibit a range of clinical behavior and may be associated with underlying syndromes. This review summarizes the clinicopathologic spectrum of smooth muscle tumors involving the skin.

Michelin tire baby syndrome: a review of the literature and a proposal for diagnostic criteria with adoption of the name circumferential skin folds syndrome

The term Michelin tire baby (MTB), named for the cartoon mascot of the Michelin Tire Company, has been used to describe babies with multiple symmetric circumferential rings of folded skin. In those reported with this phenotype who had skin biopsies, pathology has shown nevus lipomatosis, smooth muscle hamartoma, degenerative collagen, and scarring. Others did not undergo biopsy or had normal skin. Many individuals with the MTB phenotype have had a variety of other congenital anomalies. I review the literature on MTB and the history of the designation Michelin tire baby Syndrome (MTBS). Because the term MTBS has been poorly defined or not defined at all, I propose strict criteria for diagnosis. In doing so, it is recommended that the syndrome be renamed to avoid further confusion.

Generalized smooth muscle hamartoma with multiple congenital anomalies without the "Michelin tire baby" phenotype

We report a patient with generalized smooth muscle hamartoma who presented with many of the variety of congenital anomalies that have been reported in babies with multiple symmetric circumferential rings of folded skin known as Michelin tire baby (MTB) syndrome, but our patient did not show the MTB phenotype. This constellation of findings in the absence of the MTB phenotype has not been previously reported.

New syndrome of congenital circumferential skin folds associated with multiple congenital anomalies

Congenital circumferential skin folds can be found in individuals with no additional defects, as well as in patients with multiple congenital anomalies and developmental abnormalities. Current data point to etiological heterogeneity of syndromic cases. We describe a 7-month-old girl with a novel combination of symmetrical congenital circumferential skin folds, dysmorphic features, and multiple congenital abnormalities. Examination of the patient revealed symmetrical congenital circumferential skin folds and dysmorphic features, as well as multiple congenital anomalies including nasal pyriform aperture stenosis, ventricular septal defect, absent spleen, camptodactyly, and severe psychomotor retardation. Skin biopsy demonstrated subcutaneous fat extending into the superficial and deep reticular dermis. Sequencing of the CDON, SHH, ZIC2, SIX3, and TGIF genes (associated with holoprosencephaly) did not disclose pathogenic alterations. Extensive review of previously described cases of syndromic congenital circumferential skin folds did not reveal a similar combination of clinical and histopathological findings.

Circumferential skin creases, cleft palate, typical face, intellectual disability and growth delay: "circumferential skin creases Kunze type"

Congenital symmetrical circumferential skin creases are a rare feature, often described as the "Michelin Tire Baby" syndrome and in general having a good prognosis. In some patients however, the circumferential skin creases are associated with other congenital malformations. We describe 2 unrelated patients presenting with multiple circumferential skin creases, growth retardation, developmental delay, a typical facial appearance and cleft palate. In literature, 6 patients with an almost identical clinical phenotype have been described. This well recognizable syndrome should be distinguished from the "Michelin Tire Baby" syndrome and we therefore propose the term "circumferential skin creases Kunze type".

A case of Michelin tire baby syndrome with a thickened epiglottis

Multiple circumferential skin folds have been reported as part of the Michelin tire baby syndrome (MTBS). There has been a wide spectrum of associated clinical findings reported in children with MTBS. We report a case of MTBS associated with a thickened epiglottis.

Multiple congenital anomalies/mental retardation syndrome with multiple circumferential skin creases: a new syndrome?

We describe a combination of multiple congenital anomalies, a severe psychomotor retardation and seizures in a 9-year-old Tunisian boy with circumferential ringed skin creases. He had symmetrical circumferential skin creases on arms, legs, and penis. Craniofacial anomalies included: an elongated face, tight forehead, hypertelorism, bilateral epicanthic folds, upslanting palpebral fissures, microphthalmia, convergent strabismus, wide nasal bridge, aberrant teeth, dental caries, and low-set posteriorly rotated ears with overfolded thick helices. He had also ureterocele, hypospadias, and others anomalies. The magnetic resonance imaging of the brain showed hypoplastic vermis, hypoplastic corpus callosum, and dilatation of ventricles. Chromosomal analysis revealed a normal male karyotype with 46,XY. Skin biopsy was normal. To the best of our knowledge, this combination of anomalies has not been reported and this case may be a unique syndrome.

Generalized congenital smooth muscle hamartoma presenting with hypertrichosis, excess skin folds, and follicular dimpling

We describe an interesting patient with a diffuse smooth muscle hamartoma who presented with hypertrichosis, increased skin folds, and follicular dimpling. While smooth muscle hamartoma classically presents as a small hairy, skin-colored to hyperpigmented patch or plaque, rare presentations with diffuse involvement or follicular papules have been described. We present our patient and review the literature to highlight the diverse and under recognized manifestations of this benign neoplasm.

Congenital smooth muscle hamartoma: the importance of differentiation from melanocytic nevi

Congenital smooth muscle hamartoma (CSMH) is a rare cutaneous lesion commonly seen on the trunk or extremities as a localized skin-colored or mildly hyperpigmented and irregularly shaped patch or plaque with prominent vellus hairs. Histologically, CSMH is characterized by the proliferation of intersecting bundles of smooth muscle. The clinical differential diagnosis of CSMH includes congenital melanocytic (pigmented) nevus, Becker's melanosis, solitary mastocytoma, piloleiomyoma, café-au-lait spots, and nevus pilosus. Differentiating CSMH from a congenital melanocytic nevus avoids the unnecessary excision of this benign condition.

Michelin tire syndrome: a report of two siblings

Michelin tire syndrome is a rare syndrome characterized by excessive folding of the skin. The diagnosis is mainly clinical. It has been found to be associated with noncutaneous anomalies, and probably reflects multiple underlying disorders. We report two siblings with Michelin tire syndrome, a 5-year-old boy and his sister both of whom had marked skin folds and facial anomalies. Histologic study found an increase in smooth muscle fibers of the dermis. Electron microscopy showed details of smooth muscle cells. We also review reported cases in the literature to contribute to a better understanding of this syndrome.

Spontaneously improving Michelin tire baby syndrome

Michelin tire syndrome is described in a 22-month-old girl of Indian origin who had generalized folding of the skin, esotropia, epicanthic folds, and delayed speech. Histopathology showed diffuse lipomatous hypertrophy. The skin changes showed partial improvement on follow-up. We report this case because of its rarity. Furthermore, the spontaneous improvement is significant, unlike the persistent course of other congenital nevi.

A second patient with MCA/MR syndrome with multiple circumferential skin creases

Symmetrical congenital circumferential skin creases are a rare feature described in only a few conditions. We report a case of a 29-month-old boy with symmetrical circumferential skin creases on arms, legs, and digits, and other features reminiscent of the single case reported by Cohen et al. [1993: Clin Dysmorphol 2:39-46] and reviewed by Elliott et al. [1996: Am J Med Genet 62:23-25]. The key features also include epicanthic folds, microphthalmia, microcornea, microcephaly, small, low-set posteriorly angulated ears with thick overfolded helices, cleft palate, and moderate-severe psychomotor developmental delay.

Raised limb bands developing in infancy

Congenital cutaneous constriction bands are rare and often occur with other abnormalities, including the presence of rudimentary digits. This diverse syndrome lacks a precise definition and a satisfactory explanation. We describe two unusual cases with features previously undescribed, in which predominantly raised, annular limb bands became apparent postnatally. One infant was also born with foreshortened digits and a constricting limb band, suggesting a shared aetiology with other congenital cases. The development of raised bands during infancy would be difficult to reconcile with the widely held 'amniotic band hypothesis', and would be more in keeping with a multifocal developmental abnormality in limb growth.

Cutaneous smooth muscle neoplasms: clinical features, histologic findings, and treatment options

Cutaneous smooth muscle is present in 3 separate locations: arrector pili muscles, blood vessel walls, and genital/areolar skin. Benign or malignant smooth muscle neoplasms may arise from each of these locations. This review discusses the pathogenesis, clinical manifestations, histologic findings, prognosis, treatment options, and controversial areas of cutaneous smooth muscle neoplasms. ( J Am Acad Dermatol 2002;46:477-90.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be able to discuss the pathogenesis, clinical manifestations, histologic findings, prognosis, and treatment options of cutaneous smooth muscle neoplasms.

Congenital smooth muscle hamartoma presenting as a linear atrophic plaque: case report and review of the literature

Congenital smooth muscle hamartoma usually manifests as a well-circumscribed, hyperpigmented plaque, frequently hypertrichotic, on the trunk or extremities. We report such a lesion in a 7-month-old girl that presented as a linear, mottled, purplish red plaque appearing in areas to be atrophic, involving her right buttock, posterior thigh and leg, and fifth toe. Although the clinical appearance suggested linear morphea, a biopsy specimen had numerous haphazardly oriented bundles of smooth muscle in the reticular dermis. Masson trichrome staining, smooth muscle specific actin, and electron microscopic studies confirmed the smooth muscle nature of the cells. A diagnosis of smooth muscle hamartoma was made. To our knowledge, this linear clinical presentation has not been described previously.

Folded skin with an underlying cutaneous smooth muscle hamartoma

We report a 3-month-old male infant with marked folding of the skin, who manifested mental retardation and delayed growth at the age of 31 months. Histological examination of the folded skin disclosed smooth muscle hamartomatous changes. To our knowledge, this represents the third reported case of folded skin with an underlying smooth muscle hamartoma.

Congenital smooth muscle hamartoma of the skin

A 2-month-old white girl had a congenital, tan-colored, slightly elevated, 3 x 2-cm plaque on the left midback. Clinically, the lesion was suspected to be a solitary mastocytoma. Rubbing the lesion produced a transient erythema and edema that was similar to Darier sign seen in mastocytoma. Analysis of a skin biopsy specimen revealed a smooth muscle hamartoma; special stains did not show evidence of increased numbers of mast cells. This relatively uncommon condition can be confused with a variety of other cutaneous diseases. Light microscopic examination of a skin biopsy specimen establishes the diagnosis. A review of the approximately 50 cases reported in the literature showed that there is no known associated systemic involvement or malignant transformation. The clinical lesions usually become less prominent with time.