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 Table of Contents  
Year : 2019  |  Volume : 16  |  Issue : 2  |  Page : 141-144

Subcutaneous fat necrosis: A case report

1 Neonatal Unit Department of Paediatrics, Faculty of Clinical Sciences, Zaria, Kaduna State, Nigeria
2 Department of Pathology, Faculty of Basic Clinical Sciences, Zaria, Kaduna State, Nigeria
3 Plastic and Reconstructive Surgery Division, Department of Surgery Faculty of Clinical Sciences, College of Health Sciences, Ahmadu Bello University/Teaching Hospital, Zaria, Kaduna State, Nigeria

Date of Submission20-Dec-2017
Date of Decision12-Feb-2018
Date of Acceptance11-Mar-2018
Date of Web Publication19-Nov-2019

Correspondence Address:
Dr. Abdulkadir Isa
Neonatal Unit, Department of Paediatrics, Faculty of Clinical Sciences, College of Health Sciences, Ahmadu Bello University/ Teaching Hospital, Zaria, Kaduna State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njbcs.njbcs_42_17

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Subcutaneous fat necrosis (SCFN) is a rare dermatologic condition which until recently was thought to occur only in term neonates. Its presentations are protean and early in the disease; it mimics other more common neonatal dermatologic conditions. Although benign, it runs a prolonged course and may be associated with some complications and therefore needs to be differentiated from other more life-threatening neonatal dermatologic conditions. We present a case of a term neonate with histology report highlighting some characteristic features of SCFN and the need to differentiate it from sclerema neonatorum (SN), a condition associated with fatal outcome.

Keywords: Adiponecrosis subcutanea, neonate, panniculitis, sclerema neonatorum, subcutaneous fat necrosis

How to cite this article:
Isa A, Nazir U, Usman B A, Muhammad L A. Subcutaneous fat necrosis: A case report. Niger J Basic Clin Sci 2019;16:141-4

How to cite this URL:
Isa A, Nazir U, Usman B A, Muhammad L A. Subcutaneous fat necrosis: A case report. Niger J Basic Clin Sci [serial online] 2019 [cited 2020 Apr 6];16:141-4. Available from: http://www.njbcs.net/text.asp?2019/16/2/141/271004

  Introduction Top

Subcutaneous fat necrosis (SCFN) is a rare dermatologic condition exclusive to childhood. It belongs to a group of diseases categorized as panniculitis with varying and poorly understood aetiopathogenesis but is generally characterized by inflammation of the subcutaneous fat.[1],[2],[3],[4],[5],[6],[7],[8] It is postulated, however, that affected neonates share an underlying biochemical defect in the composition and metabolism of fat which, in turn, predisposes them to this condition.[1] Subcutaneous fat of neonates is characterized by high ratio of saturated fatty acids in comparison to adult fat; some have hypothesized that this encourages hardening at lower body temperatures while others have postulated that hardening results from decreased mobilization of fatty acid because of defect in lipophilic enzymes or in lipid transport mechanism.[1],[2] A little more than 200 cases of SCFN have been reported since it was first described in 1926.[9] Although initially thought to occur only in term babies, few reports now suggest that it occurs in preterm babies.[10],[11],[12] It has been associated with a variety of conditions including maternal medical conditions such as gestational diabetes, dyslipidemia, preeclampsia, hypertension, use of cocaine, smoking, use of calcium channel blocker in pregnancy, and maternal thrombosis, while perinatal situations including asphyxia, cold injury, and traumatic delivery have also been suggested to play a role.[10],[11],[12],[13],[14] The presentation is protean, but generally dermatologic features may include multiple or single skin lesions. Lesions are initially discrete but may later coalesce to form large plaques and are found mostly on the gluteal region, thighs, shoulders, back, cheeks, and arms.[3],[6],[9] Although a benign self-remitting condition, SCFN should be differentiated from sclerema neonatorum (SN) considered by some to be a harbinger of fatal outcome in severe neonatal conditions such as neonatal sepsis and regarded by others as a more aggressive and fatal panniculitis of the newborn.[4],[7] Confirmatory diagnosis is by histology including fine needle aspiration biopsy for cytology but more so with deep tissue biopsy histology.[15],[16],[17] This report aims at reporting a case with some characteristic histologic features and gives consideration to the possibility of it being a member of a spectrum of panniculitis of the newborn and the need to differentiate it from SN.

  Case Report Top

A term baby boy delivered to a 38-year-old grand multipara (P10+0), through emergency caesarean section because of antepartum hemorrhage and prolonged labor, was presented at 72 h of life with complaints of thickening and abnormally dark skin pigmentation over his right arm, gluteal region, and left thigh.

The lesions were first noticed 24 h after birth as reddish discoloration over the left thigh and buttock, which later became progressively darkened and thickened. There was associated pain as the baby became increasingly irritable when the lesions were touched. There was no prior history of trauma to the site or insect stings.

Pregnancy was booked and essentially uneventful. However, labor was prolonged and complicated by antepartum hemorrhage which necessitated delivery by caesarean section. There was no history of meconium-stained liquor. The baby cried few minutes after birth following stimulation and administration of supplemental oxygen through nasal prongs. Apgar scores were 5 and 7 at the first and fifth minutes of life, respectively.

At presentation to the special care baby unit (SCBU), he was irritable, febrile (T = 37.7°C), mildly pale, icteric, and had areas of dark pigmentation involving the right arm, ipsilateral scapular and gluteal region, and the lateral aspect of his left thigh. The lesions were indurated, tender, and with no well-defined borders. There were no areas of ulcerations or discharge [Figure 1]a, [Figure 1]b, [Figure 1]c].
Figure 1: (a-c) Clinical photographs of lesions with subcutaneous fat necrosis

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A diagnosis of early-onset sepsis with bacterial cellulitis was made with a differential of SCFN of the newborn. The baby was investigated accordingly; blood culture yielded no bacterial growth; electrolytes and urea were normal; serum calcium and phosphates were 2.67 and 1.87 mmol/L, respectively; complete blood count revealed the following: packed cell volume (PCV) 0.30 L/L, white blood cell (WBC) 15.6 × 109/L, and platelets 272 × 109/L (normal appearing).

The baby was started on intravenous clindamycin (10 mg/kg/dose 8 hourly) and metronidazole (7.5 mg/kg/dose 8 hourly). At 16 days of life, the lesions were noticed to have become fluctuant over the left gluteal region and thigh. At the age of 21 days, the primary lesions have extended to involve the left leg. Fever had subsided, and the baby was feeding well and gaining adequate weight. Incision and drainage of the fluctuant area were done, and 20 mL of straw-colored pus-like fluid was drained, which yielded no growth on culture. The patient gradually improved and stabilized, tolerated feeds, and gained weight, and drainage sites healed with dressings. He had incisional biopsy of the leg lesion which included skin and subcutaneous tissue taken on the 23rd day of life. The site healed after primary closure, and he was discharged and being followed up.

Histology report showed a wedge-shaped skin biopsy which measured 15 × 10 × 5 mm and weighed 2 g. Cut sections revealed grey fatty appearance. Histology revealed subcutaneous lesion exhibiting foci of necrotic adipocytes. The lesion was composed of lymphocytes and macrophages, the latter forming granuloma in an area. An isolated multinucleate giant cell was noted. Other areas showed fibrosis, dystrophic calcification, and cholesterol clefts within necrotic adipocytes [Figure 2]a-d]. A conclusion of SCFN was made.
Figure 2: (a) Skin Biopsy showing a subcutaneous lesion within lobules of adipocytes. H/E ×40 magnification. (b) Skin biopsy at higher magnification (H/E ×100) showing mononuclear cellular infiltrates, fibrosis and dystrophic calcification. (c) H/E × 400 magnification showing Granuloma with fat Necrosis composed of histiocytes, multinucleate giant cell and necrotic adipocytes. (d) Necrotic adipocytes showing cholesterol clefts and dystrophic calcification. H/E ×1000 magnification

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  Discussion Top

SCFN of the newborn is a rare and commonly missed panniculitis. The case under review had some of the risk factors commonly associated with SCFN. These include the presence of neonatal stress: antepartum hemorrhage, prolonged labor, and the eventual resuscitation at birth. The appearance, pattern, and progression of the skin lesions which began with lesions on the back of the trunk, the gluteal region, and the thigh with somewhat symmetry of the lesions also support the diagnosis. The initial association of fever, reddening, and tenderness with subsequent fluctuancy in some of the lesions made cellulitis with abscess formation and neonatal sepsis undismissable differential diagnoses and hence the imperative empirical use of antibiotics for treatment. However, with the progression, evolution, and coalition of lesions into plaques with darkening of the skin, the diagnosis of SCFN became even more appealing. SN, a common association of severe sepsis and formerly considered a harbinger of fatal outcome, was clinically distinguishable from SCFN as it causes diffuse thickening of the skin unlike SCFN where nodules or plaques are characteristic as in this report. Scleroderma (SD) on the other hand is prominently associated with edema, which was absent in this case. Other authors[6],[10] have also reported similar cases of SCFN; literature, however, has not emphasized the association of SCFN with sepsis. On the other hand, Brain[18] reported a case with histologic finding of both SN and SCFN a rare finding. It may, therefore, be that panniculitis of the newborn is a spectrum of a single disease on a severity scale with perhaps SN being the severest form while the eventual manifesting type is defined by possibly the degree and extent of exposure to risk factors in susceptible neonates. These put together pose both diagnostic and management plan challenge which requires clarification to define extent of treatment bearing in mind the fatal outcome associated with SN as against SCFN and the other more invasive interventions such as exchange blood transfusion and use of steroids that may be used as lifesaving in SN. This thus highlights the importance of the need for histologic diagnosis for optimal management.

Classically, fat necrosis is absent in both SN and SD but characteristic of SCFN. Other findings associated with SCFN in addition to patchy areas of fat necrosis include inflammatory infiltrates with foreign-body giant cells, eosinophils, and lymphocytes.[15],[16],[17] Additional findings may include foamy macrophages, multinucleated giant cells, lymphocytes, neutrophils, and radially arranged, refractile, needle-shaped crystals visible in the cytoplasm of the fat cells loosely lying in the necrotic background. Histologically, the lesion in this index case was in keeping with panniculitis characterized by foci of fat necrosis, lymphoplasma infiltrates in the subcutis, and fat microcysts[15],[16],[17] but devoid of perivascular distribution of the inflammatory infiltrates in the lower half dermis all in keeping with SCFN. Both SN and SD are associated with alteration of collagen in the dermis. And particularly[4],[7] SD is not uncommonly associated with eosinophils and crowded thickened bundles of collagen arranged parallel to one another and to the skin surface. In this lesion, there was no associated eosinophilic infiltrates; the collagen bundles were neither thickened nor crowded; and the fibrosis was not marked significantly. Sclerema, on the other hand, is commonly associated with the absence of inflammatory infiltrates and fat necrosis and the presence of pronounced fibrosis much more than in SCFN. Unlike in SN, there was no evidence of mucin (mucosubstance) deposition in the stroma of this lesion.

Incisional biopsy provides opportunity to harvest tissue for histology which remains the hallmark of diagnosis.[15],[16],[17] For optimal results, punch biopsy should include harvest of subcutaneous fat,[14] although fine needle aspiration biopsy cytology is considered by others as an alternative to tissue biopsy.[16],[17] For better yield of results, biopsies should be obtained through an elliptical incision with primary closure avoiding sites of active or healed inflammation.

SCFN may be associated with complications which include hypercalcemia, hypoglycemia, hypertriglyceridemia, thrombocytopenia, ulceration of the lesions, bacterial infection, and abscess formation involving the area of fat necrosis.[16],[17] The baby in this case report did not have any of this commonly associated complications[16],[17] as serum calcium and platelet counts were within normal range; however, this is not unexpected as hypercalcemia is usually noticed 4–6 weeks after documenting the skin lesions.[17] Some of the lesions became fluctuant which could have been a result of liquefaction of the subcutaneous fat, but the aspirate was found to contain purulent material which did not yield any organism suggesting possibly a sterile abscess particularly more so as the baby had received antibiotics. Chikaodinaka and Jude in southeast Nigeria[10] documented similar findings in their report of a case with SCFN who presented with abscesses complicating the panniculitis.

Panniculitis of the newborn appears to be a spectrum of a disease entity with SN being the severest form. It may be difficult to differentiate the individual entities during the early stage of illness. Healthcare providers caring for newborns should be aware and be on the lookout for SCFN which remains a rare and benign dermatological condition. SCFN needs to be differentiated from SN by paying attention to clinicopathologic details and confirmation using appropriate biopsy technique and histology to enable elaborate and optimal management plan for the neonate.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Zeb A, Darmstadt GL. Sclerema neonatorum: A review of nomenclature, clinical presentation, histological features, differential diagnoses and management. J Perinatol 2008;28:453-60.  Back to cited text no. 1
Requena L. Normal subcutaneous fat, necrosis of adipocytes and classification of the panniculitides. Semin Cutan Med Surg 2007;26:66-70.  Back to cited text no. 2
Fenniche S, Daoud L, Benmously R, Ben Ammar F, Khelifa I, Chaabane S, et al. Subcutaneous fat necrosis: Report of two cases. Dermatol Online J 2004;10:12.  Back to cited text no. 3
Torrelo A, Hernández A. Panniculitis in children. Dermatol Clin2008;26:491-500.  Back to cited text no. 4
Warwick WJ, Ruttenberg HD, Quie PG. Sclerema neonatorum sign, not a disease.JAMA 1963;184:680-3.  Back to cited text no. 5
Oliveira ACS, Selores M, Pereira O. Fat necrosis of the newborn: Report on two cases. An Bras Dermatol 2011;86:114-7.  Back to cited text no. 6
Grassi S, Borroni RG, Brazzelli V. Panniculitis in children. G Ital Dermatol Venereol 2013;148:371-85.  Back to cited text no. 7
Browne KW, Burman D. Subcutaneous fat necrosis of the newborn. Int J Obstet Gynaecol 1958;65:819-22.  Back to cited text no. 8
Burden AD, Krafchik BR. Subcutaneous fat necrosis of the newborn: A review of 11 cases. Pediatr Dermatol 1999;16:384-7.  Back to cited text no. 9
Chikaodinaka AA, Jude AC. Subcutaneous fat necrosis of the newborn: A case report of a term infant presenting with malaise and fever at age of 9 weeks. Case Rep Pediatr 2015;2015:1-5.  Back to cited text no. 10
Coondoo A, Lahiry R, Choudhury A, Sengupt S. Tender skin nodules in a newborn. Indian J Dermatol 2013;58:328.  Back to cited text no. 11
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Gupta RK, Naran S, Selby RE. Fine needle aspiration cytodiagnosis of subcutaneous fat necrosis of newborn. A case report. Acta Cytol 1995;39:759-61.  Back to cited text no. 13
Tomasini C, Lentini F, Borroni G. The role of skin biopsy in diagnosis of panniculitides. G Ital Dermatol Venereol 2013;148:335-49.  Back to cited text no. 14
Schubert PT, Razack R, Vermaak A, Jordaan HF. Fine-needle aspiration cytology of subcutaneous fat necrosis of the newborn: The cytology spectrum with review of the literature. Diagn Cytopathol 2012;40:245-7.  Back to cited text no. 15
Tran JT, Sheth AP. Complications of subcutaneous fat necrosis of the newborn: A case report and review of the literature. Pediatr Dermatol 2003;20:257-61.  Back to cited text no. 16
Alaoui K, Abourazzak S, Oulmaati A, Hida M, Bouharrou A. An unusual complication of subcutaneous fat necrosis of the newborn. BMJ Case Rep 2011;2011:bcr1220103569.  Back to cited text no. 17
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