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Acquired generalized lipodystrophy (AGL) is a rare disease characterized by variable loss of adipose tissue and concurrent metabolic derangements, typically with childhood or adolescent onset. AGL has three subclassifications: panniculitis (type 1), autoimmune disease (type 2), and idiopathic (type 3). This report highlights a rare case of AGL type 1 in a previously healthy 3-year-old female who presented with diffuse erythematous subcutaneous nodules, progressive lipoatrophy, and histopathological findings of a lobular panniculitis., (© 2024 Wiley Periodicals LLC.)

Self-induced trauma is a rare cause of panniculitis in adolescents and may be associated with undiagnosed underlying psychological conditions. The condition often poses a diagnostic challenge as patients usually present with non-specific signs and symptoms, and often a concealed history of self-induced trauma. Here, we present three adolescent patients with self-induced traumatic panniculitis. All three patients were repeatedly admitted with non-specific cutaneous lesions as well as multiple somatic complaints. After extensive evaluation to exclude organic causes, psychiatric assessment eventually revealed underlying psychosomatic disorders as a cause of the self-induced trauma., (© 2022 Wiley Periodicals LLC.)

Infection-induced panniculitis has been described in association with a broad range of microorganisms. Among those, viral panniculitis represents a minor category, with only a few anecdotal reports in the literature documenting viral infection in the subcutaneous fat. Herein, we report a woman in her 30s with seropositive rheumatoid arthritis on rituximab and prednisone, who presented with a 6-month history of progressive multisystem manifestations, including unintentional weight loss, fever, fatigue, myopathy, pancreatitis, and sensorineural hearing loss. She had indurated plaques on her thighs characterized by predominantly lobular panniculitis with chronic lymphohistiocytic inflammation. Molecular studies performed at the Centers for Disease Control and Prevention identified evidence of Enterovirus group with the highest identity of Coxsackievirus A9. Enterovirus RNA was also detected in the cerebrospinal fluid and muscle. Based on the findings, a diagnosis of disseminated enteroviral infection in the setting of B-cell depletion was rendered. To the best of our knowledge, this represents the first reported case of viral panniculitis with documentation of Coxsackievirus A9 in the skin. Since rituximab may be used for the treatment of autoimmune dermatological diseases, familiarity of the potential occurrence of severe enteroviral infections in the setting of immunosuppressive treatment is important for dermatopathologists., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Talimogene laherparepvec (T-VEC) is a novel intralesional oncolytic genetically modified herpes simplex virus type 1 vector for the treatment of unresectable cutaneous, subcutaneous, and nodal melanoma. Although immunological therapies such as T-VEC offer therapeutic promise, they carry a risk of immune-related adverse events (irAEs), the full spectrum of which is incompletely understood. We report a 63-year-old previously healthy man with cutaneous melanoma of the right ankle and progressive right lower extremity in-transit metastases despite systemic therapy with immunomodulatory and molecularly targeted treatments. T-VEC treatment resulted in a complete pathologic response on scouting biopsies. Biopsy of the right lateral calf showed lobular and septal panniculitis with lymphoplasmacytic infiltrate and lipophages. Gomori methenamine silver (GMS) stain and acid-fast bacilli (AFB) stains were negative, and no polarizable foreign material was noted. T-VEC was discontinued due to complete pathologic response and, in part, concern for development of irAEs including this panniculitis and an early concomitant autoimmune colitis. This case highlights a previously unreported irAE with this novel treatment for advanced cases of melanoma., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Lyme disease classically evolves through clinical manifestations according to the stage of illness. Because many of the systemic symptoms are non-specific, and because serology may yield false negative results, cutaneous findings merit even greater importance to diagnosis. The prototypical skin lesion, erythema migrans (EM), occurs early and is the only independent diagnostic clinical feature according to the guidelines of the Infectious Diseases Society of America. EM itself has protean guises, being, at times, vesicular, indurated, necrotic, purpuric, solid, or targetoid, but it is not the sole Borrelia-associated skin lesion. Acrodermatitis chronica atrophicans and borrelial lymphocytoma cutis are other well-known skin manifestations. A rare cutaneous manifestation that is increasingly reported in Lyme patients is panniculitis, which develops after dissemination of the spirochete. We present such a case in a patient who was initially treated for cellulitis as well as neck and radicular leg pain, thereby expanding the cutaneous spectrum of Lyme disease., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

To understand features of human obesity and type 2 diabetes mellitus (T2D) that can be recapitulated in the mouse, we compared C57BL/6J mice fed a Western-style diet (WD) to weight-matched genetically obese leptin receptor-deficient mice ( db/db ). All mice were monitored for changes in body composition, glycemia, and total body mass. To objectively compare diet-induced and genetic models of obesity, tissue analyses were conducted using mice with similar body mass. We found that adipose tissue inflammation was present in both models of obesity. In addition, distinct alterations in metabolic flexibility were evident between WD-fed mice and db/db mice. Circulating insulin levels are elevated in each model of obesity, while glucagon was increased only in the db/db mice. Although both WD-fed and db/db mice exhibited adaptive increases in islet size, the db/db mice also displayed augmented islet expression of the dedifferentiation marker Aldh1a3 and reduced nuclear presence of the transcription factor Nkx6.1. Based on the collective results put forth herein, we conclude that db/db mice capture key features of human T2D that do not occur in WD-fed C57BL/6J mice of comparable body mass.

Postirradiation pseudosclerodermatous panniculitis is a rare complication of external beam radiotherapy. This inflammatory process typically presents as an erythematous indurated plaque in a previously irradiated region of skin. To date, 13 cases have been reported worldwide. We present a case of a 70-year-old female who received breast irradiation following conservation surgery for invasive breast carcinoma. In her third year of follow-up, she developed an enlarging mass, involving the subcutis and underlying breast tissue, associated with mammographically detected coarse calcifications and density, at the surgical site. This was deemed highly suspicious of recurrent malignancy. Following several benign needle core biopsies, she had an excision of the mass. This revealed a lobular panniculitis and irradiation-induced vascular changes affecting subcutaneous fat and underlying breast tissue. This is the 14th reported case of this rare entity. It is unique in the degree of involvement, affecting breast parenchyma as well as subcutaneous fat, and in its corresponding dramatic clinical and radiographic manifestations., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) characterized by subcutaneous infiltration of pleomorphic T-cells of the α/β phenotype rarely affects children. Development of hemophagocytic syndrome (HPS) leads to a poor prognosis with this otherwise indolent lymphoma. We report a case of SPTCL in a 5-year-old child complicated by HPS treated successfully with combination chemotherapy. We discuss the potential pitfalls in reaching an early diagnosis and challenges in its management. Previously reported cases of SPTCL with HPS in children are briefly reviewed., (© 2016 Wiley Periodicals, Inc.)

Herein, we describe two cases and review 14 cases of equestrian chilblain or 'equestrian cold panniculitis' in the literature. The first, a 23-year-old healthy female horse trainer, presented with burning nodular swelling on her lateral thighs. The second was a 34-year-old healthy woman with recurrent nodular eruption on the lateral thighs after horseback riding in the winter. Physical examination of both patients revealed erythematous to violaceous nodules with eczema craquelé-like changes. Laboratory workup for systemic and autoimmune connective tissue disease was negative. Punch biopsies from both patients showed a superficial and deep perivascular and periadnexal lymphocytic infiltrate with focal extension into the subcutaneous fat. Parakeratosis, subtle spongiosis and increased pandermal interstitial mucin were also present. Previously reported cases generally showed a similar clinical course and similar histopathologic findings. In contrast, our cases revealed increased pandermal interstitial mucin, resembling tumid lupus erythematosus. We aim to better characterize the histopathologic findings of equestrian chilblain and discuss its relationship to other cold-induced skin injuries and autoimmune connective tissue disease, namely lupus erythematosus., (Copyright © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.)

Subcutaneous fat necrosis of the newborn is a form of panniculitis that most often occurs in full-term infants with predisposing risk factors. Three neonates with hypoxic ischemic encephalopathy were treated with therapeutic hypothermia and developed extensive subcutaneous fat necrosis. All three infants developed extensive subcutaneous fat necrosis, involving the back, scalp, and arms. Mild, asymptomatic hypercalcemia was noted in one infant in the weeks following the subcutaneous fat necrosis. Hypothermia as a risk factor for subcutaneous fat necrosis is reviewed. Clinicians should be aware of subcutaneous fat necrosis as a possible risk factor and complication associated with asphyxiated newborns who may undergo therapeutic hypothermia. Future studies for therapeutic hypothermia should evaluate neonates for the development of subcutaneous fat necrosis., (© 2011 Wiley Periodicals, Inc.)

An infiltrate mimicking subcutaneous panniculitis associated with a granulomatous response represents an uncommon histopathologic presentation of lymphoma. We report three cases, comprising one case each of nasal-type extranodal NK/T-cell lymphoma, cutaneous γ/δ T-cell lymphoma and human T-lymphotropic virus-I associated adult T-cell leukemia/lymphoma, which based on initial histopathologic and/or clinical presentation were thought to represent systemic lupus erythematosus, sarcoidosis and psoriasiform dermatitis, respectively. Excisional biopsies of indurated lesions performed at our institute; however, in each case showed an atypical subcutaneous lymphohistiocytic infiltrate associated with a variable number of granulomas. Extensive immunophenotypic characterization, in conjunction with histomorphologic and molecular analysis, established the diagnosis of lymphoma in all instances. All patients had a rapidly progressive clinical course and death was attributable to complications of lymphoma shortly after diagnosis. These cases highlight the importance of using a multimodality diagnostic approach to distinguish lymphomas masquerading as granulomatous panniculitis from inflammatory or reactive disorders associated with such histopathologic patterns., (Copyright © 2011 John Wiley & Sons A/S.)

Ice therapy has long been used as first line treatment of supraventricular tachycardia in neonates. We report a case of cold panniculitis developing in a 12-day-old neonate after ice therapy for cardiac arrhythmia. This is the first biopsy-proved case of cold panniculitis following ice therapy for supraventricular tachycardia in a newborn., (© 2010 Wiley Periodicals, Inc.)

Systemic sclerosis (SSc) is an autoimmune systemic disease characterized by small vessel involvement that leads to tissue ischemia and fibroblast stimulation resulting in accumulation of collagen (fibrosis) in the skin and internal organs. Lipomembranous panniculitis is a peculiar type of fat necrosis and has been reported with clinical conditions, commonly with peripheral vascular diseases. We describe a case of a 43-year-old woman with SSc manifestations, who presented with black scaly skin plaques, associated with thickening of the subcutaneous fat tissue, on the lateral surface of her thighs, her calves, gluteal area and lower abdomen. Biopsy revealed lipomembranous panniculitis. Lipomembranous changes have been seen in connective tissue disorders such as lupus profundus, morphea, systemic sclerosis and panniculitis associated with dermatomyositis, but rarely in thighs, calves, gluteal area and lower abdomen., (Copyright © 2009 John Wiley & Sons A/S.)

Panniculitis is an uncommon condition in childhood and may prove difficult to diagnose both clinically and histologically. The clinical spectrum is similar to that in adults and has been associated with many primary diseases. Noninfectious causes are less common in children than in adults. The pathogenesis remains uncertain in a significant number of children. In some it may be a malignant, unremitting disease which can be fatal. We present a boy aged 13 years with panniculitis of the right foot as presenting sign for the ultimate diagnosis myelodysplasia-acute myeloid leukemia. To our knowledge this is the first report on a young boy.

Adequate clinical data and a sufficient workup, in addition to the histopathological findings, are frequently required to make a correct diagnosis of granulomatous dermatitis/panniculitis. These lesions with an unexpected etiology may include delayed hypersensitivity granulomatous reactions to various factors, such as metals or marine animal injuries. A 50-year-old male presented with multiple subcutaneous nodules on his right forearm 1 month following an octopus bite at his right wrist. After the disappearance of these lesions, which responded well to low-dose oral prednisone, another type of skin lesion characterized by small, numerous papules reappeared on his right forearm. Histopathologically, a specimen from a subcutaneous nodule showed mostly lobular granulomatous panniculitis, which showed an extensive diffuse infiltrate composed of numerous multinucleated giant cells and epithelioid cells intermingling with lymphocytes and eosinophils. A specimen from a papule that subsequently developed disclosed a diffuse granulomatous dermatitis composed of similar cells and also showed granuloma annulare-like features. This case is considered to be a delayed reaction after an octopus bite showing an unusual giant cell-rich granulomatous dermatitis/panniculitis. Octopus bites should therefore be included among the marine animal injuries, which cause a delayed-type reaction with granulomatous dermatitis/panniculitis.

Pancreatic panniculitis is an uncommon disorder with a distinctive histopathology. We report the youngest patient with pancreatic panniculitis caused by hypertriglyceridemia in association with nephrotic syndrome.

Erythema nodosum (EN) is the most common panniculitis and histologically represents the prototype of a septal panniculitis. However, the histologic findings can be quite variable. We describe four patients with EN who each underwent two consecutive biopsies. In each case, the first biopsy showed histopathologic features that fall outside the usual spectrum of disease. Two cases showed predominantly neutrophilic infiltrates with focal suppuration as well as vasculitis of medium-sized arteries. The areas of suppuration were more extensive in the first case prompting special stains for microorganisms that were all negative. The third case demonstrated a lobular panniculitis with a predominantly lymphohistiocytic infiltrate. Special stains were negative in this case as well. The fourth case revealed vasculitis of a medium sized artery, small vessel vasculitis, and a mixed septal and lobular panniculitis with a polyclonal population of atypical lymphocytes. In all patients, the clinical course and the subsequent biopsy were classic for EN. We conclude that lobular neutrophilic panniculitis with suppuration, small vessel vasculitis, and even medium vessel arteritis may rarely occur in EN. There are few clues in these unusual cases that allow for a specific diagnosis from the start, and often, a second biopsy is required.

Background: Cutaneous findings other than hyperpigmentation are rare in Whipple's disease., Case Report: We present the case of a 59-year-old man previously diagnosed with Whipple's disease by duodenal biopsy, who developed red-brown, painful, subcutaneous nodules on the buttocks, thighs, arms and legs. Biopsy of these nodules showed a septal panniculitis and foamy macrophages containing PAS-positive, diastase resistant intracytoplasmic material, characteristic of Whipple's disease and similar to that observed in the duodenal biopsy. Ultrastructurally, this material in the histiocytes corresponded to degenerated bacilli., Conclusions: This is the fourth documented case of subcutaneous involvement by Whipple's disease. One should consider the possibility of Whipple's disease in any patient who presents with symptoms compatible with that condition who demonstrates septal panniculitis with a large amount of foamy histiocytes.

Panniculitis is a rarely reported clinical finding in dermatomyositis. We present a 14-year-old African American boy with a 4-year history of dermatomyositis referred for evaluation of tender, indurated plaques and nodules on the trunk and proximal extremities. A biopsy specimen revealed epidermal and dermal changes consistent with dermatomyositis. Although calcification was absent, a striking lobular panniculitis was observed. A total of seven cases of clinical panniculitis in association with dermatomyositis have been published. As in our patient, it typically presents as indurated, tender plaques and nodules on the arms, thighs, and buttocks. Although in the vast majority of cases panniculitis found in association with dermatomyositis is subclinical and represents an incidental histopathologic finding, the case we present further emphasizes the need to recognize panniculitis as a rare, but clinically relevant pathologic feature seen in certain lesions of juvenile dermatomyositis.

Background: Eosinophilic fasciitis and the related fasciitis panniculitis syndrome (FPS) are the clinical and morphologic expression of a variety of disorders, of which chronic inflammation and fibrous thickening of the subcutaneous septa, fascia, and perimysium are common. FPS in patients with cancer has been reported sporadically., Methods: In the course of our studies of FPS we have encountered three patients who had an associated neoplasia. Nine reports of patients have been taken from the literature. The clinical and histologic data of FPS in the 12 patients were analyzed in the search of distinctive features from FPS in patients with no evidence of malignancy., Results: Among patients with cancer-associated FPS there was a female predominance (8 patients), predilection for hematolymphatic malignancies (9 patients), precedence of the FPS to cancer diagnosis (10 patients) by a median lag time of 1 year, and unresponsiveness to prednisone therapy in most patients (7 of 8 patients)., Conclusions: Cancer-associated FPS has several characteristics of a paraneoplastic syndrome: it occurs at a distance from the tumor, certain types of tumors are overrepresented among patients with FPS, it evolves in concert with the neoplasia, and it sometimes remits after successful cancer surgery. In contrast to idiopathic FPS, cancer-associated FPS shows a female predominance, and it usually fails to respond to corticotherapy.

The clinical spectrum of cutaneous M. tuberculosis infections is varied and atypical. Once a major cause of death, with the advent of antimicrobial drugs it had, until recently, been an uncommon consideration in the differential diagnosis of cutaneous disorders. Panniculitis can be caused by a variety of etiologic agents; however, only rarely has it been reported caused by tuberculosis. Herein, we describe a patient with an unusual case of neutrophilic panniculitis caused by M. tuberculosis that arose following corticosteroid therapy for presumptive polymyositis. This case illustrates the need to include mycobacterial infection in the differential diagnosis of panniculitis in immunocompromised patients, and the importance of early detection via microbiologic culture and histopathologic examination.

We evaluated the histopathologic findings in 15 cases of panniculitis due to infection. Organisms were identified by special staining in 14 cases, and in 6 of these the etiologic agent was confirmed by culture studies. In one additional case, lesional culture was positive despite negative special staining. Eight cases were caused by gram positive or gram negative bacteria, 2 by atypical mycobacteria, 2 by Nocardia, and 3 by fungi (Candida and Fusarium species). Most patients had conditions or were receiving therapies predisposing to immunosuppression, but at least 2 individuals had no other major medical problems. There were some variability in microscopic findings and overlap with established forms of panniculitis; 3 cases (2 due to bacteria and 1 to Fusarium) resembled acute, "neutrophilic" erythema nodosum, and evidence of vasculitis was seen in septicemias due to Pseudomonas, Nocardia, and Fusarium. Nevertheless, several distinctive features associated with infectious panniculitis of diverse etiologies included: epidermal alterations such as acanthosis and parakeratosis; dermal edema with a diffuse or perivascular neutrophilic infiltrate; and mixed septal-lobular panniculitis with neutrophilic infiltration, vascular proliferation and hemorrhage, and necrosis. Infection should be suspected in virtually any case of panniculitis, particularly when occurring in an immunosuppressed patients, but the microscopic features enumerated above should arouse particular suspicion of an infectious process.