Nodular-Cystic Fat Necrosis -A Review of 147 Japanese Patients

Masanori Ban

Masanori Ban, Ban skin clinic, Private practice, Hashima, Japan

Conflict-of-interest statement: The author(s) declare(s) that there is no conflict of interest regarding the publication of this paper.

Correspondence to: Ban Hifuka, Masakicho Magari 1050-1, Hashima City, 501-6227, Japan. Email: banhifuka@major.ocn.ne.jp
Telephone: +81-58-391-0056

Received: August 2, 2016
Revised: August 20, 2016
Accepted: August 22, 2016
Published online: December 26, 2016


Nodular-cystic fat necrosis, which is also called encapsulated fat necrosis, is a mobile subcutaneous nodule and histologically reveals fat necrosis encapsulated by fibrous connective tissue. In Japan, many cases have been reported, and there are some opinions that diabetes mellitus and systemic corticosteroid therapy cause this condition. The author found that out of 147 Japanese patients reported from 1982 up to 2015, 9 had the former and 23 received the latter. Systemic corticosteroid therapy may be responsible for nodular-cystic fat necrosis.

Key words: Nodular-cystic fat necrosis; Japanese patients; Systemic corticosteroid therapy

© 2016 The Author(s). Published by ACT Publishing Group Ltd. This is an open access article under the CC BY-NC-ND license (http: //creativecommons.org/licenses/by-nc-nd/4.

Ban M. Nodular-Cystic Fat Necrosis - A Review of 147 Japanese Patients. Journal of Dermatological Research 2016; 1(4): 65-68 Available from: URL: http: //www.ghrnet.org/index.php/jdr/article/view/1807


Many cases of nodular-cystic fat necrosis have been reported by Japanese. It is a subcutaneous nodule and histologically reveals fat necrosis encapsulated by fibrous connective tissue (Figure 1). Most lesions have mobility[1]. This condition has several names. The term “nodular-cystic fat necrosis” was proposed by Przyjemski & Schuster in 1977[2]. Sahl[3] reported two cases as “mobile encapsulated lipoma” the next year. He mentioned encapsulated adipocytes and thrombi, but did not do the presence of fatty degeneration. In 1984 Kikuchi et al[4] thought Sahl’s cases identical to nodular-cystic fat necrosis and emphasized that “mobile encapsulated lipoma” was a more suitable term. At the same time Kikuchi[5] reported two cases showing advanced necrosis, membranocystic change and no mobility. He concluded them to be different from mobile encapsulated lipoma. In 1989 Hurt & Santa Cruz[1] stated that the above cases belong to a spectrum consisting of the different fatty degeneration and the mobility depends on the quantity of surrounding soft tissue. They preferred the term “nodular-cystic fat necrosis.” Now membranocystic change is considered a nonspecific pattern of fat necrosis[6].

Figure 1 A subcutaneous nodule composed of fat necrosis and surrounded by fibrous tissue (× 10).

In Japan, a mother country of Kikuchi, the concept of this condition was confused. At first, three terms mainly were used: “nodular-cystic fat necrosis”, “mobile encapsulated lipoma” and the Japanese name proposed by Ichiki et al[7] in 1987, which could be translated to “encapsulated fat necrotic small nodule (Kikuchi)”. This Japanese name was succinctly translated to “encapsulated fat necrosis (Kikuchi)” by Ezoe et al[8]. Two English papers using “encapsulated fat necrosis” in the titles were written by Japanese dermatologists in 1997 and 2000[9,10]. This term became popular not only in Japan but around the world. “Mobile encapsulated lipoma” is rarely used now.

Hurt & Santa Cruz[1] described that fat degeneration progresses with time. In the early stage the construction of the adipose tissue is kept, but most areas show no nuclei. Vascular structure and blood cells are found (Figure 2). The middle stage lesions show degenerated honeycomb patterns of anucleated adipocytes, focal or massive hemorrhage, vascular thrombosis and lipomembranous change (Figure 3). The late stage lesions reveal fibrosis, hyalinization and calcification. The construction of the adipose tissue mostly are not found (Figure 4)[1,11,12]. A very few lesions disappear spontaneously[13,14]. The pathogenesis is thought to be rapidly compromised blood supply, presumably from trauma, in the adipose tissue[1]. Some cases have been reported, which were associated with complications: erythema nodosum[15], Ehlers-Danlos syndrome[8], Heerfordt’s syndrome[16], splinter granuloma[17], systemic sclerosis[14], lupus erythematosus[18], and juvenile dermatomyosiits[19]. Local ischemia in skin may be induced by them. In Japan several authors suspect diabetes mellitus[20-23] and systemic corticosteroid therapy[13,14,24,25] as etiologies of nodular-cystic fat necrosis. It is speculated that diabetic microangiopathy causes local ischemia in the patients with the former and that skin atrophy, subcutaneous hemorrhage and panniculitis do it in ones who received the latter. Shibata et al[24] suggested that it is a dermadrome of Cushing syndrome which reveals high levels of cortisol.

Figure 2 Anucleated fat cells and veins including red cells in the early stage (× 100).

Figure 3 Degenerate veins and membranocystic change in the middle stage (× 100).

Figure 4 Fibrosis and calcification in the late stage (× 100).

Searching Pub Med, Ichushi service (Japanese online medical service by NPO Japan Medical Abstracts Society) and previous views[10,23], the author found 147 Japanese patients with this condition reported from 1982 up to 2015 in English and Japanese literature, and analyzed their complications.

The number of lesions was multiple in 79 patients, single in 52 and unknown in 16 patients. The youngest was a one-year old female. Female patients between the ages of 40 and 69 predominated (Table 1). About 60% lesions occurred in the lower extremities which are easy to receive trauma (Table 2). The history of trauma was evident in only 26 patients, and frequent in the young (Table 1). The reason may be because they have many opportunities playing sports. The present analysis did not indicate the participation of diabetes mellitus. Only 9 patients (6%) had it (Table 3). Prevalence of diabetes in Japanese adults (20-79 years) is 7.6% (International Diabetes Federation 2015). However, it is important that 8 out of 9 patients had multiple lesions. Twenty-three patients (15.6%) had taken systemic corticosteroid therapy (Table 3). Twenty out of them had multiple lesions. These numbers make us suspect possibility that it causes nodular-cystic fat necrosis. Enough information was not obtained about the doses and the dosing period.

The author hopes more reports about complications from the world.

Table 1 Distribution of age, sex and trauma history
agenumber of malenumber of male with the history of traumanumber of femalenumber of female with the history of trauma

Table 2 Site of the lesions
sitenumber of patients
lower leg65
upper arm4
lumbus 8

Table 3 Complications and systemic corticosteroid therapy
underlying diseasenumber of patientsnumber of patients receiving systemic corticosteroid therapy
systemic lupus erythematosus76
rheumatoid arthritis32
systemic lupus erythematosus + rheumatoid arthritis11
systemic sclerqderma + Sjogren's syndrome + Basedow's disease11
Sogren's syndrome + anti-phospholipid antibody syndrome + systemic lupus erythematosus11
autoimmune hepatitis11
pemphigus vulgaris11
hypereosinophilic syndrome11
granulomatosis with polyangiits11
Sheehan's syndrome11
chronic inflammatory demyelinating polyneuropathy11
Cushing's syndrome20
Ehlers-Danlos syndrome10
multiple sclerosis10
sarcoidosis ( including Heerfordt's syndrome)20
Behcet'ss disease 1 0
Daibetis melitus 7 0
Daibetis melitus + rheumatoid arthritis
1 0
Daibetis melitus + polyneuritis 1 1
Unknown   4


I wish to thank Prof. Mariko Seishima (Gifu University) for her help.


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Peer reviewer: Mohammed Alsufyani


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