Diagnosis
Classification
It can occur in any fatty tissue (cutaneous or visceral) and is often diagnosed on the basis of a deep skin biopsy, and can be further classified by histological characteristics based on the location of the inflammatory cells (within fatty lobules or in the septa which separate them) and on the presence or absence of vasculitis.There are thus four main histological subtypes:
lobular panniculitis without vasculitis (acute panniculitis, previously termed Weber–Christian disease, systemic nodular panniculitis)
lobular panniculitis with vasculitis
septal panniculitis without vasculitis
septal panniculitis with vasculitis

Lobular
With vasculitis
Erythema induratum, or "Bazin disease", is a panniculitis on the back of the calves. It was formerly thought to be a reaction to the tuberculum bacillus. It is now considered a panniculitis that is not associated with a single defined pathogen.Nodular vasculitis is a skin condition characterized by small, tender, reddened nodules on the legs, mostly on the calves and shins. Microscopically there are epithelioid granulomas and vasculitis in the subcutaneous tissue, making it a form of panniculitis. Most of these cases are now thought to be manifestation of tuberculosis and indeed they respond well to anti-tuberculous treatment. Without vasculitis
Non-vasculitis forms of panniculitis that may occur include:

Cytophagic histiocytic panniculitis was first described in 1980 by Winkelmann as a chronic histiocytic disease of the subcutaneous adipose tissue, which is characterized clinically by tender erythematous nodules, recurrent high fever, malaise, jaundice, organomegaly, serosal effusions, pancytopenia, hepatic dysfunction and coagulation abnormalities. : 494  CHP may occur either isolated or as part of cutaneous manifestations of hemophagocytic syndrome (HPS).
Other confounding conditions contributing to ORS are thick and profuse pelvic adhesions, inflammation, bleeding after surgery (peri-operative bleeding), and ovaries which are retroperitoneal, can all contribute to the unintentional preservation of ovarian fragments. Risks
The risk of ovarian remnant (ORS) is increased by incomplete removal of the ovary at the time of oophorectomy. Surgical factors that contribute to incomplete removal include those that limit surgical exposure of the ovary, or compromise surgical technique. Factors may include:

adhesions – these can limit visualization of the ovary and may also cause it to adhere to surrounding tissues. Adhesions are often present due to preexisting conditions and/or prior surgeries. In the majority of cases reported since 2007, endometriosis was the most common indication for the initial oophorectomy in patients who subsequently had ORS. Endometriosis increases the risk for functional ovarian tissue being embedded into adjacent structures, making complete excision of tissue challenging. Anatomic variations - unusual location of ovarian tissue, for example
Intraoperative bleeding
Poor surgical technique – this may include failure to obtain adequate exposure or restore adequate anatomy, or imprecise choice of incision siteOvarian remnant (ORS) may first be considered in women who have undergone oophorectomy and have suggestive symptoms, the presence of a mass, or evidence of persistent ovarian function (by symptoms or laboratory testing). A history of oophorectomy is required, by definition, to make the diagnosis. Notes regarding the indication for the procedure and the procedure itself should be reviewed and may include prior abdominal or pelvic surgery, endometriosis, and/or poor surgical visualization.