Interstitial Granulomatous Dermatitis: A Clinicopathological Analysis Of 4 Cases

Background: Interstitial granulomatous dermatitis(IGD)is an uncommon granulomatous dermatitis occurring in the setting of highly reactive immune states,with characteristic pathological features of interstitial histiocytic infiltration in dermal tissue,and a variety of clinical manifestations.The cause of the disease is still unknown,often associated with systemic diseases,may be related to immune factors,or induced by certain drugs,and certain foods such as soybeans and shells,may also be involved in the pathogenesis.The disease needs to be differentiated from other granulomatous diseases.The therapeutic experience is still unsatisfactory.Glucocorticoids are one of the classical treatment methods.In addition,immunosuppressants and biological agents have been reported for treating IGD successfully.Objective: To study and analyze the clinical manifestations and histopathological features of interstitial granulomatous dermatitis and review the literature.Methods: The cases in this study had previously diagnosed with interstitial granulomatous dermatitis,from January 2014 to December 2017.(1)Clinical data: collect medical history,assess clinical variables,including gender,age,duration,type and distribution of lesions,accompanying symptoms,with or without systemic disease,laboratory tests,treatment,follow-up.(2)Histopathology2.1 Review the pathological sections of the selected cases and have them reviewed by 2skin histopathologists.All cases met the following histopathological criteria: Interstitial infiltrate predominantly composed of histiocytes surrounding small foci of collagen fragmentation with scattered neutrophils and/or eosinophils.2.2 Assessment of histopathological parameters included the topography of the inflammatory infiltrate,distribution of inflammatory infiltrates,cellular compositions,collagen changes,nuclear dust,vasculitis,and extent of inflammatory infiltrates.Whether there is "floating" sign,"floating" sign that the histiocytic rosettes surrounding an empty space centred by degenerated collagen fibre,forming small focal granuloma[3].Result: General Information: A total of 4 patients were enrolled,including 2 males and2 females,male: female 1:1;aged 30 to 72 years;duration ranged from 1 week to 6months.Clinical manifestations: red or mauve macule(1/4),red or purplish red plaque(3/4),red nodules(1/4),red or purple papules(1/4).Lesions mostly attended to involve the lower extremities,followed by the upper extremities and the trunk.Distribution characteristics of lesion: 3 cases showed symmetry,1 case showed unilateral.Lesions were asymptomatic(2/4),pain and tenderness(2/4),and itching(2/4).Accompanying symptoms: joint pain(1/4),fever(1/4).Associated systemic disease: rheumatoid arthritis and type 2 diabetes(1/4),Sjogren's syndrome(1/4),mild anemia(1/4).Laboratory findings: ESR and CRP were elevated in two case(2/4),abnormal ANA spectrum were in two case(2/4),blood glucose and urinary glucose were increased in one case(1/4).Histopathological features: All biopsy specimens showed a moderate to dense,diffuse inflammatory infiltrate throughout the whole dermis composed mostly of histiocytes that distributed interstitially and focally in palisaded arra y around small,discrete bundles of sclerotic collagen(piecemeal fragmentation).The sign of "floating" were seen in two cases.Infiltrates of histiocytes and lymphocytes were observed in all cases,some specimens were accompanied by a small amount of eosinophils and plasma cells(2/4).Non of neutrophil infiltration was observed.Mucin deposition was seen in one case(1/4).All case showed perivascular inflammation and lack of vasculitis.Conclusions:1.The clinical manifestations of interstitial granulomatous dermatitis are various,this study showed that the lesions could be red,purple macule,papules,plaques,nodules,or edematous infiltrative plaque.The lesions were mainly involving the trunk and limbs,symmetrically distributed,could also be unilateral distribution.2.Histopathology is characterized by interstitial infiltration of the full layer of dermal tissue,or surrounding the focal degenerated collagen("floating" sign),which may be accompanied by a small amount of eosinophils,plasma cell infiltration,with or withnot deposition of mucin,and lack of vasculitis.3.Interstitial granulomatous dermatitis may be associated with rheumatoid arthritis,Sjogren's syndrome and other systemic diseases.4.Key histopathologic characteristics,along with clinical correlation,can allow accurate diagnosis and identify a patient who may have an underlying systemic disease.