590 SA MEDICAL JOURNAL VOLUME 64 1 OCTOBER 1983
Infantile myofibromatosis - a solitary
A case report
A. KATZ, A. E. MILLS
subcutis. In contrast, the multicentric lesions frequently invplved
bone as well as viscera. 4
Infantile myofibromatosis (IM) usually manifests
itself within the first 6 months of life, and is frequently
present at birth. The hard, rubbery nodules may be The patient, a healthy female infant, was the product of an
either solitary or multiple. Solitary lesions are more uneventful pregnancy and was born at term by normal vaginal
common and have a marked tendency to occur in delivery. Shortly after birth she was examined by a paediatrician,
boys, while the less common multicentric disorder who discovered a mass in the right paravertebral region; no other
predominantly· affects girls. Solitary nodules are abnormality was apparent. On the 3rd day oflife she was referred
usually located in the deep soft tissues, involving to one of us (A.K.), who was able to palpate a well-defined
skeletal muscle, and usually occur in the head and subcutaneous cystic mass measuring approximately 3 x 3 cm to
neck region or trunk. The prognosis of the solitary the right of the midline in the lumbodorsal region. The mass was
type of lesion is excellent, the recurrence rate being not attached to the overlying skin, but the latter was slightly
very low, and distinction from the other fibromatoses erythematous. Radiographs showed mild scoliosis to the right in
of infancy is important. A case of solitary infantile the lumbodorsal region, but no other abnormality was present.
myofibromatosis occurring as a congenital lesion of The infant was kept under observation and seen 3 weeks later, at
the back in a female infant is described. which stage the lesion was noted to be translucent. She con-
tinued to thrive, although the lesion appeared to be enlarging
S AIr Med J 1983: 64: 590-591.
slightly. At the age of 3 months it was excised. The lesion was
found to be lying in the right paraspinal muscles beneath the
deep fascia and to be unattached to spinous or transverse
processes. It was excised completely together with a rim of
The multicentric variety of infantile myofibromatosis (IM) has surrounding muscle. The appearances were similar to those of a
been widely reported in the literature under various synonyms. sternomastoid tumour. The patient recovered uneventfully, but
Stout' introduced the term 'congenital generalized fibromato- she has been referred to an orthopaedic surgeon because of
sis'. Other terms used have been 'multiple mesenchymal hamar- persistence of the scoliosis to the right.
tomas'2 and 'multiple vascular leiomyomas of the newborn'.3
However, it has only recently been established by Chung and
Enzinger4 that there is a solitary form of this disorder, which
indeed appears to be the more common manifestation. These
authors reviewed cases of childhood fibromatoses recorded by The resected specimen consisted of an oval-shaped mass
the Armed Forces Institute of Pathology in Washington, DC, measuring 4,5 x 2,5 x 2 cm. The tumour appeared encapsulated
over a 24-year period. They established 61 cases with similar and encased within a surrounding rim of muscle. On section it
pathological features, which they termed 'infantile myofibroma- was seen to be cystic with a central necrotic area containing clear
tosis'. Forty-five patients (31 boys and 14 girls) had a solitary
rumour, while 16 (6 boys and 10 girls) had multicentric tumours.
A tumour had been present since birth in 33 cases. Of43 patients
who were followed up for at least 1 year, only 3 of28 patients with
a solitary tumour had a single recurrence. In the multicentric
tumour group 12 of 15 patients were alive and well, 5 patients
demonstra,ing spontaneous regression, while 3 patients had died
shortly after birth. Solitary tumours tended to be commonest in
the deep soft tissues of the head and neck or trunk, where they
involved skeletal muscle, although in a few instances they
occurred in the extremities and occasionally involved bone or
(less commonly) were superficially located in the dermis or
Departments of Surgery and Pathology, University of Cape
Town and Red Cross War Memorial Children's Hospital,
A. KATZ, CH.M., F.R.C.S.
A. E. MILLS, M.B. B.CH., D.c.r. Fig. 1. Macroscopic appearance of the gross specimen after
transection, showing the external surface (left) and the cut
Date recei\"ed: 29 !'\ovember 1982. surface (right).
SA MEDIESE TYDSKRIF DEEL 64 1 OKTOBER 1983 591
fluid surrounded by a zone of firm grey fibrous tissue about 0,5
cm in thickness (Fig. I). On histological examination the tumour
was found to be composed of a central necrotic area associated
with dilated vascular channels and ricWv vascular tissue in which
some focal dystrophic calcification w~s present (Fig. 2). This
inner portion was surrounded by a cellular zone showing a
whorled pattern composed of fascicles of smooth-muscle-like
cells interspersed with collagen-rich fibroblastic elements (Fig.
3). On ultrastructural examination the smooth-muscle-type cells
exhibited myofibroblast-like features with spindly densities,
dense plaques and external laminae (Fig. 4). Some cells showed
prominent peripheral micropinocytic vesicles. The tumour had a
distinct edge separating it from surrounding skeletal muscle.
The appearances were those of IM as described by Chung and
Enzinger. 4 These authors point our that occasionally the vaso-
formative elements in the centre of the lesion may resemble
haemangiopericytoma on histological examination.
Fig. 4. Ultrastructural appearance of the cellular zone in which a
myofibroblast with a surrounding collagen-rich matrix is seen.
Spindly densities, dense plaques and attenuated external lamina
are apparent (uranyl acetate and lead citrate x 7000).
and sometimes have a tendency to recur, there is no tendency to
metastasize. Table I lists most types of fibromatoses seen in
infancy and childhood. Usually the pathological features con-
sidered in conjunction with the site of the lesion facilitate a
precise diagnosis, bur a diagnosis of aggressive fibromatosis may
be difficult to establish with certainty and indeed it may be
impossible to distinguish this lesion from the inherently malignant
fibrosarcoma, with its proclivity for recurrence and distant
spread. The appearance of smooth-muscle-like cells in some of
the fibromatoses probably indicates the potential of the fibroblast
to undergo differentiation to a myofibroblasr.
Fig. 2. Histological appearance of the inner aspect of the tumour
showing prominent vascular proliferation (H and E reduced by . TABLE I. FIBROMATOSES OF INFANCY AND CHILDHOOD
half from x 100).
Infantile myofibromatosis (solitary or multiple)
Recurrent digital fibromatosis
Fibrous hamartoma of infancy
Palmar and plantar fibromatosis
Juvenile aponeurotic calcifying fibroma
Visceral and skeletal fibromatosis
The recently recognized entity of IM (of either solitary or
multicentric type) constitutes an important addition to the
spectrum of fibromatoses, and it is believed that the case under
discussion is the first to be reported from South Africa. 6
Fig. 3. Histological appearance of the outer cellular zone of the REFERENCES
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spontaneous regression of multiple congenital mesenchymal hamartomas.
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3. Lin 11, Svoboda DJ. Multiple vascular leiomyomas in several organs of a
newborn. Cancer 1971; 28: 1046-1053.
Discussion 4. Chung EB, Enzinger FM. Infantile myofibromatosis. Cancer 1981; 48:
5. Rosenberg MS, Stenback WA, Spjut HJ. The fibromatoses of infancy and
The characteristics of the fibromatoses are clinically and patho- childhood. In: Rosenberg MS, Bolande RP, eds. PerspeClives in Pediarric
logically relevant, mainly because of the importance of distin- Palhologv, voL 4. Chicago: Year Book Medical Publishers, 1978: 269-348.
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guishing this group of lesions from fibrosarcoma, with which it African Division of the International Academy of Pathology (Short Course No.
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