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).