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Minor Anomalies: Clues to More Serious Problems and to the Recognition of Malformation Syndromes
Minor anomalies are herein defined as unusual morphologic features that are of no serious medical or cosmetic consequence to the patient. The value of their recognition is that they may serve as indicators of altered morphogenesis in a general sense or may constitute valuable clues in the diagnosis of a specific pattern of malformation. Those who want a more detailed discussion of this subject or those who desire information on a minor malformation not addressed in this chapter are referred to Jon M. Aase’s Diagnostic Dysmorphology . 2
Regarding the general occurrence of minor anomalies detectable by surface examination (except for dermatoglyphics), Marden and colleagues 9 found that 14% of newborn babies had a single minor anomaly. This was of little concern because the frequency of major defects in this group was not appreciably increased. However, only 0.8% of the babies had two minor defects; in this subgroup, the frequency of a major defect was five times that of the general group. Of special importance were the findings in babies with three or more minor anomalies. This was found in only 0.5% of babies, 10 and 90% of them had one or more major defects as well, as depicted in Fig. 3.1 .
Frequency of major malformations in relation to the number of minor anomalies detected in a given newborn baby.
From Marden PM, Smith DW, McDonald MJ: J Pediatr 64:357, 1964, with permission.
In two additional studies, Mehes and colleagues 10 and Leppig and colleagues 8 demonstrated that 26% and 19.6% of newborn infants with three or more minor anomalies, respectively, had a major malformation, a much lower incidence than that documented in the study by Marden and colleagues and most likely related to differences in study design. Based on these studies, it is concluded that any infant with three or more minor anomalies should be evaluated for a major malformation, many of which are occult.
These minor external anomalies are most common in areas of complex and variable features, such as the face, auricles, hands, and feet. Before ascribing significance to a given minor anomaly in a patient, it is important to note whether it is found in other family members. Almost any minor defect may occasionally be found as a usual feature in a particular family, as noted in Fig. 3.2 .
An otherwise normal father (A) and daughter (B) with a pit on the chin. An otherwise normal mother (C) and daughter (D) with a torus deformity of the palate. A family history should be obtained before ascribing significance to a given minor anomaly.
Figs. 3.3 to 3.8 illustrate certain minor anomalies and allude to their developmental origin and relevance. Many, if not most, minor anomalies represent deformations caused by altered mechanical forces affecting the development of otherwise normal tissue. The reason for the deformation may be purely external uterine constraint. Thus, most minor anomalies of external ear formation at birth are constraint-induced. However, the minor deformational anomaly may be the result of a more primary malformation, and this is the presumed reason for the association between minor anomalies and major malformations.
Minor anomalies of the ocular region.
A and B, Inner epicanthal folds appear to represent redundant folds of skin, secondary to either low nasal bridge (most common) or excess skin, as in cutis laxa. Minor folds are frequent in early infancy, and as the nasal bridge becomes more prominent, they are obliterated. C, A unilateral epicanthal fold ( arrow ) is indicative of torticollis. Slanting of the palpebral fissures seems to be secondary to the early growth rate of the brain above the eye versus that of the facial area below the eye. For example, the patient with upslanting (D) had mild microcephaly with a narrow frontal area, resulting in the upslant; the patient with downslanting (E) had maxillary hypoplasia, resulting in the downslant. Mild degrees of upslant were noted in 4% of 500 normal children. F, “Ocular hypertelorism” refers to widely spaced eyes. A low nasal bridge will often give rise to a visual impression of ocular hypertelorism. This should always be determined by measurement. Measurement of inner canthal distance, coupled with the visual distinction of whether telecanthus is present, is usually sufficient. G, Brushfield spots ( arrow ) are speckled rings about two-thirds of the distance to the periphery of the iris. There is relative lack of patterning beyond the ring. These spots are found in 20% of normal newborn babies, but they are found in 80% of babies with Down syndrome.
C, From Jones MC: J Pediatr 108:702, 1986, with permission.
Minor anomalies of the oral region.
A, Prominent lateral palatal ridges may be secondary to a deficit of tongue thrust into the hard palate, allowing for relative overgrowth of the lateral palatal ridges. This ridge may be a feature in a variety of disorders, especially those with hypotonia and with serious neurologic deficits related to sucking. As such, it can be a useful sign of a long-term deficit in function. B, Lack of lingular frenulum and single central incisor. Indicative of holoprosencephaly.
Minor anomalies of the auricular region.
A, Preauricular tags, which often contain a core cartilage, appear to represent accessory hillock of His, the hillocks that normally develop in the recess of the mandibular and hyoid arches and coalesce to form the auricle. B, Preauricular pits may be familial; they are twice as common in females as in males and are more common in blacks than in whites. Both pits and tags should initiate evaluation of hearing. C, Large ears are often caused by intrauterine constraint, as in this child with oligohydramnios. Asymmetric ear size can be secondary to torticollis as in D. The child’s head was positioned constantly on his right side, leading to plagiocephaly and enlargement of the right ear. E, Microtia. This defect should always initiate evaluation for hearing loss. Of children with unilateral microtia, 85% have an ipsilateral hearing loss and 15% have a contralateral hearing loss as well. F, Low-set ears: This designation is made when the helix meets the cranium at a level below that of a horizontal plane that may be an extension of a line through both inner canthi. This plane may relate to the lateral vertical axis of the head. Ears slanted: This designation is made when the angle of the slope of the auricle exceeds 15 degrees from the perpendicular. Note that the findings of low placement and slanted auricle often go together and usually represent a lag in morphogenesis, because the auricle is normally in that position in early fetal life. It is important to appreciate that deformation of the head secondary to in utero constraint may temporarily distort the usual landmarks. 15 G, Branchial cleft sinuses.
Minor anomalies of the hands. 4 , 12
A and B, Creases represent the planes of folding (flexion) of the thickened volar skin of the hand. As such, they are simply deep wrinkles. The finger creases relate to flexion at the phalangeal joints; if there has been no flexion, as in B, there is no crease. 7 Camptodactyly (contracted fingers), depicted in B and C, most commonly affects the fifth, fourth, and third digits in decreasing order of frequency. It is presumably the consequence of relative shortness in the length of the flexor tendons with respect to the growth of the hand. The thenar crease is the consequence of oppositional flexion of the thumb; hence, if there is no oppositional flexion, there will be no crease, as in D and E.
The slanting upper palmar crease reflects the palmar plane of folding related to the slope of the third, fourth, and fifth metacarpophalangeal joints. The midpalmar crease is the plane of skin folding between the upper palmar crease and the thenar crease. Any alteration in the slope of the third, fourth, and fifth metacarpophalangeal planes of flexion, or relative shortness of the palm, may give rise to but a single midpalmar plane of flexion and thereby the simian crease, as in A. This is found unilaterally in approximately 4% of normal infants and bilaterally in 1%. Davies 6 found the incidence to be 3.7% in newborn babies and noted that the simian crease is twice as common in males as in females. All degrees are found between the normal and the simian crease, including the bridged palmar crease. The creases are evident by 11 to 12 weeks of fetal life; hence, any gross alteration in crease patterning is usually indicative of an abnormality in form or function of the hand prior to 11 fetal weeks. 7 Clinodactyly (curved finger) (F) is most common in the fifth finger and is the consequence of hypoplasia of the middle phalanx, normally the last digital bone to develop. Up to 8 degrees of inturning of the fifth finger is within normal limits. Regardless of which digits are affected (fingers or toes), there is usually incurvature toward the area between the second and third digits. Partial cutaneous syndactyly represents an incomplete separation of the fingers and most commonly occurs between the third and fourth fingers and between the second and third toes. The nails generally reflect the size and shape of the underlying distal phalanx; hence, a bifid nail (G) reflects dimensions of the underlying respective phalanges (H), as does the hypoplastic nail shown in I. Malproportionment or disharmony in the length of particular segments of the hand is not uncommon. The most common is a short middle phalanx of the fifth finger with clinodactyly. F, Another anomaly is relative shortness of the fourth or fifth metacarpal or metatarsal bone. This is best appreciated in the hand by having the patient make a fist and observing the position of the knuckles, as shown in J. The altered alignment of these metacarpophalangeal joints may result in an altered palmar crease, especially the simian crease. It may also yield the impression of partial syndactyly between the third, fourth, and fifth fingers. Such relative shortness of the fourth and fifth metacarpals may develop postnatally by earlier-than-usual fusion of the respective metacarpal epiphyseal plates. When this occurs, it tends to do so in the center of the epiphyseal plate first, yielding the radiographic appearance of a cone-shaped epiphysis. This is a nonspecific anomaly that may occur by itself or as one feature of a number of syndromes.
Minor anomalies of the feet.
A and B, Syndactyly (most commonly between digits 2 and 3). If, as in A, its degree is less than one-third of the distance from the base of the first phalanx to the distal end of the third, it is considered a variation of normal, whereas in B it is greater than one-third of that distance and is thus considered a minor malformation. C, Clinodactyly of the fifth toe with overlapping. D, Short fourth metatarsal making the fourth toe appear short. E, Hypoplasia of nails.
Minor anomalies of genitalia.
A, Shawl scrotum appears to represent a mild deficit in the full migration of the labial-scrotal folds and, as such, may be accompanied by other signs of incomplete masculinization of the external genitalia. This photo shows a patient with Aarskog syndrome. B, Hypoplasia of the labia, which may in some cases give rise to the false visual impression of a large clitoris. C, Median raphe is caused by testosterone-induced fusion of the labioscrotal folds in a normal male. It is never seen in a 46,XX individual unless there has been abnormal secretion of androgen.
Calvarium
The presence of unusually large fontanels (see standards in Chapter 4 ) may be a nonspecific indicator of a general lag in osseous maturation. 13 It may, for example, lead to the detection of congenital hypothyroidism in the newborn or young infant, as shown in Fig. 3.9 . 16 The finding of a large posterior fontanel is especially helpful in this regard, because the posterior fontanel is normally fingertip size or smaller in 97% of full-term neonates. Large fontanels may also be a feature in certain skeletal dysplasias and can, of course, be a sign of increased intracranial pressure.
Dermal Ridge Patterns (Dermatoglyphics)
The parallel dermal ridges form on the palms and soles of the fetus between weeks 13 and 19. Their patterning appears to be dependent on the surface contours at the time, and the parallel dermal ridges tend to develop transversely to the planes of growth stress. 11 Curvilinear arrangements occur when there is a surface mound, for example, over the fetal pads that are prominently present during early fetal life on the fingertips, on the palm between each pair of fingers, and occasionally in the hypothenar area. Indirect evidence suggests that a high fetal fingertip pad tends to give rise to a whorl pattern, a low pad yields an arch pattern, and an intermediate pad produces a loop, as illustrated in Fig. 3.10B . The dermal ridge patterning thereby provides an indelible historical record that indicates the form of the early fetal hand (or foot). Mild to severe alterations in hand morphology occur in a variety of syndromes, and hence it is not surprising that dermatoglyphic alterations have been noted in numerous dysmorphic syndromes. These alterations have seldom been pathognomonic for a particular condition. Rather, they simply provide additional data that, viewed in relation to the total pattern of malformation, may enhance the clinician’s capacity to arrive at a specific overall diagnosis. Dermal ridge patterning may be evaluated with a seven-power illuminated magnifying device, such as an otoscope, or a stamp collector’s flashlight, which has a wider field of vision. Permanent records may be obtained by a variety of techniques. 3 , 5 , 17 There are two general categories of dermatoglyphic alterations: an aberrant pattern and unusual frequency or distribution of a particular pattern on the fingertips.
Aberrant Patterning
Distal Axial Palmar Triradius
Triradii occur at the junction of three sets of converging ridges ( Fig. 3.10A ). There are usually no triradii between the base of the palm and the interdigital areas of the upper palm. However, patterning in the hypothenar area often gives rise to a distal axial triradius located, by definition, greater than 35% of the distance from the wrist crease to the crease at the base of the third finger. This alteration, found in approximately 4% of whites, is a frequent feature in a number of patterns of malformation.
Open Field in Hallucal Area (Arch Tibial)
“Open field” simply means that there is a relative lack of complexity in patterning, and it thereby implies a low surface contour in that area at the time that ridges developed (see Fig. 3.10A ). The hallucal area of the sole usually has a loop or whorl pattern, and a lack of such a pattern is unusual in the normal individual; however, it is found in approximately 50% of patients with Down syndrome and as an occasional feature in other syndromes.
Lack of Ridges
The failure of ridges to develop in an area, most commonly the hypothenar region of the palm, is an occasional but nonspecific feature in de Lange syndrome.
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