DISCUSSON:
NL is an inflammatory dermatosis with degenerative connective tissue changes very often linked to diabetes. According to previous reports, diabetes mellitus is a common comorbidity, occurring in greater than 50% of NL patients(5, 6). In 14% of cases, NL emerges before diabetes mellitus is diagnosed. In 24% of cases, NL appears concurrently with the onset of diabetes. In the remaining 62% of cases, NL emerges after diabetes has already been diagnosed. However, our patient did not mention any history of diabetes and her blood glucose levels were within normal range during the visit to dermatology clinic. Additionally, her NL lesion was located on her elbow rather than the more common pretibial area. This represents a deviation from the typical NL lesions being localized to the lower extremities in approximately 85% of NL cases (1).
While the clinical presentation of morphea can vary significantly between patients, there is currently no universally accepted classification system. Kreuter et al.(7) have suggested a five-part categorization of morphea: limited, generalized, linear, deep, and mixed (a combination of at least two prior types). Each of these primary types can be further subdivided into various clinical subtypes. In the case presented, the patient demonstrated plaque type morphea over her trunk. plaque type morphea is classified under limited morphea and is recognized as the most common manifestation of localized scleroderma in adults.
Several studies have investigated NL comorbidities including cutaneous comorbidities. We conducted a PubMed search for articles containing “necrobiosis lipoidica” in the title or abstract. Additionally, no limitations were placed on language or year of publication for the included articles. We detected 11 retrospective articles focusing on NL comorbidities (table 1). Severson KJ et al.’s (5) research on 328 NL patients revealed that, psoriasis, scleroderma and morphea were reported as coexisting dermatoses. Similarly, a study by Jockenhöfer et al. (8) examined 262 NL patients and found psoriasis, erysipelas and other local infections of skin and subcutaneous tissues as comorbidities. In a smaller study by Erfurt-Berge et al. (9) involving 52 NL patients, cutaneous sarcoidosis was the only reported coexisting dermatosis. Finally, Marcoval, J., et al. (10) conducted a study on 35 NL cases and found granuloma annulare to be the sole cutaneous co-diagnosis. Other studies mainly focused on non-cutaneous comorbidities such as diabetes, hypertension, dyslipidemia and thyroid disease, thereby did not offer any insights into cutaneous comorbidities. These studies collectively imply that the coexistence of inflammatory and autoimmune dermatoses with NL is not uncommon. This association is likely attributable to the underlying dysregulation of the immune system, which may predispose individuals to multiple autoimmune manifestations.
Specifically, Coexistent NL and morphea has been documented only 4 times in the literature. As mentioned above, the retrospective study conducted by Severson KJ et al.(5) found that among 328 NL patients, only 3 cases were reported to have coexisting morphea. Additionally, Acebo E et al (4) reported a 59-year-old woman with morphea affecting her breast who also developed NL lesion over the scar from an appendectomy she had undergone 38 years earlier. Similar to our case she did not develop any NL lesions on pretibial area.
NL and morphea are 2 separate disease entities with noteworthy similarities and differences. Both diseases are inflammatory dermatoses with different patterns of inflammation and collagen abnormalities. Histopathologically, NL is marked by necrobiotic collagen surrounded by layered granulomatous inflammatory infiltrate. This granulomatous reaction mainly consists of dermal and subcutaneous infiltrate of histiocytes, epithelioid cells, and multinucleated giant cells with epidermis often remaining unaffected (8, 11). In contrast morphea is defined by an autoimmune fibrosing disease characterized by excessive collagen production and the presence of perivascular lymphocytic inflammatory infiltrate, particularly evident in the early stages of the disease.(4, 7). Both conditions also show a female predominance, with morphea having a female-to-male ratio of around 4:1 and NL having a ratio of around 3:1.
Dermoscopically, both NL and morphea exhibit vascular abnormalities albeit with distinct patterns. Morphea features linear branching vessels along with scattered whitish fibrotic beams and brownish reticulated areas. On the other hand, NL lesions are characterized by comma-shaped vessels during the initial phase, transitioning to arborizing vessels in the final phase, all against a yellow-white background (1, 3, 12).
Given the role of immune system dysfunction in the pathogenesis of both NL and morphea, the mainstay of treatment for these conditions is corticosteroids and immunomodulators. Additionally, phototherapy-based therapies were shown to be effective in alleviating both conditions. In fact, ultraviolet light exposure exerts anti-inflammatory effects via modulating inflammatory cytokines and depleting certain inflammatory cells (3, 7, 12).