ARTICLE
Auteur(s) :, Miho TORITSUGI*, Toshiyuki
YAMAMOTO, Kiyoshi NISHIOKA
1Department of Dermatology, Tsuchiura Kyodo General
Hospital, 11-7 Manabe-Shinmachi, Tsuchiura City, Ibaraki 300-0053,
Japan.
2Department of Dermatology, Tokyo Medical and Dental
University, School of Medicine, Tokyo, Japan
*Reprints: Miho Toritsugi. Fax. (+81)298. 23. 1160.
accepté le 15 Mars 2004
Nodular cystic fat necrosis shows mobile subcutaneous nodules in
regions vulnerable to trauma, such as extremities [1-3]. The
histological features are characterized by encapsulated fat
necrosis with lipomembranous changes showing the presence of cystic
cavities lined by crenulated, hyaline membranes. Lipomembranous
changes are histological findings without specific clinical
correlation, and are suggested to be related to vascular impairment
of the fat tissue. We herein present a case of nodular cystic fat
necrosis in a patient with systemic sclerosis (SSc). Interestingly,
lipomembranous changes were detected not only in the nodular cystic
fat necrosis, but also in the scleroderma skin biopsied from the
forearm.
Case report
A 59-year-old woman, with a history of systemic sclerosis and
Sjögren’s syndrome, visited our hospital complaining of several
subcutaneous nodules on her forearm and shin, which had appeared
5 years previously. She had suffered from systemic sclerosis
for 31 years, and had been treated with oral prednisolone for
over 20 years. Physical examination discerned multiple
elastic-hard, movable nodules, sized 5-8 mm in diameter, located on
the flexural aspect of her left forearm and both shins. The nodules
were mobile within a few centimeters. She denied a preceding
significant injury to these sites.
Three nodules on her right shin were surgically removed.
Grossly, they were pale yellow, smooth, and translucent.
Histological examination showed that they were completely
encapsulated by condensed fibrous tissues. One of the tissue
specimens showed a honeycombed structure, showing multiple small
lesions which exhibited variable amounts of fat necrosis within the
capsule (( Fig. 1A )). Peripheral
portions near the fibrous capsules are smaller and untidy
adipocytes. Periodic acid-Schiff (PAS) stain revealed
lipomembranous changes within the nodule (( Fig. 1B )). Another
specimen was acellular and composed of fat necrosis surrounded by
fibrous tissues. The calcification was confirmed by von Kossa
staining (( Fig. 2 )).
A biopsy was also taken from the extensor aspect of the forearm
for the evaluation of scleroderma, although clinically sclerosis of
the forearms was not recognized any more. The specimen revealed the
atrophic stage of scleroderma (( Fig. 3A )), and no
changes of dermal sclerosis such as either thickened collagen
bundles or deposition of homogenous materials were found. In the
subcutaneous adipose tissue, lipomembranous changes were observed
(( Fig. 3B
)).
Discussion
Nodular cystic fat necrosis was first described by Pryjemski and
Schuster [1], as an unusual, localized form of fat necrosis
characterized by discrete encapsulated fat nodules. The lower
extremity is the most commonly affected site, suggesting that
antecedent trauma and subsequent interruption of blood supply are
the main causing factors. So far, various names have been assigned
for this condition, including mobile encapsulated lipoma [4, 5],
encapsulated fat necrosis [3, 6], and encapsulated necrosis
(Kikuchi) [7], however, the majority of the cases reported under
these names are considered to be the same entity. Histologically,
nodular cystic fat necrosis shows multiple, non-viable adipocytes
surrounded by condensed fibrous tissues. Lipomembranous changes and
calcification are occasionally seen. Lipomembranous changes in the
localized lesions are suggested to be caused possibly by trauma or
ischemia, and a nonspecific pattern of fat necrosis. Recent studies
suggest that lipomembranous changes result from interaction of
residual elements of distinguished fat cell and macrophages
probably as a consequence of inflammatory and ischemic disorders of
fatty tissue [8].
Nodular cystic fat necrosis is seen in patients with erythema
nodosum [9], chronic active hepatitis [10], IgA nephropathy [10],
and Ehlers-Danlos syndrome [6]. However, association with SSc has
not been reported until now. Scleroderma often affects the
subcutaneous tissue, which thereby may be a major contributing
factor in the development of foci of necrosis in this case.
The most interesting feature in this case is that lipomembranous
lesions were noted not only in the nodules of nodular cystic fat
necrosis but also in the biopsied skin of scleroderma.
Lipomembranous changes are occasionally seen in nodular cystic fat
necrosis [6, 10], and also in various disorders associated with or
without vascular diseases [8], suggesting a nonspecific pattern of
necrosis due to interruption of the blood supply in the
subcutaneous tissues. Machinami [11] reported membranous
lipodystrophy-like changes in the specimens of amputated limbs of
SSc. They speculate that lipomembranous lesions can be caused by
chronic ischemia. On the other hand, our case did not present
necrosis of the fingers or toes, and the lipomembranous changes
were seen in the forearm skin of atrophic stage of SSc. Snow et
al. [12] reported 3 cases of morphea associated with
marked lipomembranous changes in the subcutaneous adipose tissue.
In their cases, lipomembranous changes were recognized within and
immediately adjacent to areas of fibrosis. They speculate that
lipomembranous changes may also result from a variety of causing
effects including infectious, autoimmune and physical
processes.
In end-stage lesions, fibrosis and dystrophic calcification are
often seen within the encapsulated nodules [2, 10, 13]. The
mechanisms of calcification are considered to be as follows [13];
the subcutaneous fat is prone to trauma or ischemia. Once the fat
cell is damaged, the liberated lipid then undergoes hydrolysis into
glycerol and fatty acids. The fatty acids combine with calcium,
resulting in calcification of the fat. Our case was thus considered
as end stages. We speculate that multiple, chronic, local or
systemic events causing a compromise in the blood supply of the
subcutaneous tissues may contribute to the induction of
lipomembranous changes in the affected skin as well as nodular
cystic fat necrosis in this case.
References
1 Przyjemski , Schuster Nodular-cystic fat necrosis J
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2 Hurt , Santa Cruz Nodular-cystic fat necrosis: A
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3 Kiryu , Rikihisa , Furue Encapsulated fat necrosis-A
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4 Sahl Mobile encapsulated lipomas: formerly called
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11 Machinami Incidence of membranous lipodystrophylike
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three cases J Am Acad Dermatol 31 1994 246-250
13 Oh , Kim A case of nodular cystic fat necrosis. The
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Dermatol 25 1998 616-621
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