Histologic changes in eccrine apparatus in patients with Sjogren syndrome and no evidence of anhidrosis

Sjogren syndrome (SS) is an autoimmune disease that involves salivary and lacrimal glands. There are rare articles describing hypohidrosis or anhidrosis in SS patients. Little is known about the histologic findings seen in patients with SS who do not report decreased sweating. We analyzed skin samples from 31 patients with SS who had undergone skin biopsies for reasons not related to SS. We assessed the number, distribution and pathologic changes within and around the eccrine ducts, glands and acrosyringia. The composition of the inflammatory infiltrate was additionally accessed utilizing immunohistochemical stains. Overall, in 60% of cases we observed some degree of inflammation. In virtually all cases the inflammatory infiltrate was located around the eccrine ducts at a distance from the non-SS pathology. It was mainly composed of CD3+ T cells with increasing number of B and plasma cells as periductal inflammation intensified. This study is the first histologic analysis of asymptomatic skin in patients with SS. It demonstrates the presence of skin involvement in the majority of SS patients. Our results emphasize the importance of systematic skin evaluation in this category of patients as well as counseling, early preventive measurements and timely treatment when indicated. Sjogren syndrome; xerosis; anhidrosis; eccrine apparatus

systems [12]. SS patients can develop various types of exocrine manifestations such as autoimmune thyroiditis, interstitial nephritis, or pneumonitis.
In a case that we described recently, a patient presented with markedly diminished axillary sweating. The biopsy demonstrated extensive fibrosis and a marked diminution in the number of eccrine structures, with glandular ectasia deep in the specimen. [13] Although xerosis is an extremely common symptom in advanced SS, we know very little about the exact cutaneous processes in the affected skin, its chronology and its evolution in relation to salivary and lacrimal impairments. As with other autoimmune conditions, one might expect SS to cause systemic damage to all susceptible tissues. Although clinical manifestations begin due to salivary and lacrimal glands impairment, it is unknown if these glands are the initial targets of the disease or simply the most sensitive to the inflammatory damage. It is possible that cutaneous damage might happen concurrently with damage to other exocrine glands but not demonstrate clinical manifestations for a long time. There is no data in the literature nor any documented study of subclinical skin health in patients with already manifested SS. These patients may not yet exhibit cutaneous symptoms but steadily develop microscopic skin impairments. In order to investigate for the presence of a peri-eccrine, focally destructive autoimmune process involving eccrine structures, we conducted evaluation of 31 skin biopsies performed for other reasons on patients with diagnosed SS and asymptomatic skin.

Materials and Methods
The study protocol was approved by the Institutional Review Board at the University of Rochester School of Medicine and Dentistry. This study was based on the retrospective analysis of archival tissue. The study utilized surgical pathology specimens of patients who had been diagnosed with SS over the past 15 years (January 1st, 2004 to December 31, 2019). We found 162 such patients. From these 162 initial patients, 31 patients had skin biopsies for reasons not related to their SS diagnosis and were considered to be applicable to the study. Patients who were biopsied with an aim of diagnosing or staging of SS were excluded. All analyzed cases had primary pathology previously diagnosed by the dermatopathology unit in our institution and were reviewed for inclusion in this study by one of us (BRS).
The 31 skin biopsies contained a total of 84 eccrine structures and were reviewed in order to assess the number, distribution and pathologic changes within and around the eccrine ducts and glands. Eccrine structures were interpreted as separate clusters of eccrine ducts and glands. Acrosyringia were examined as part of the eccrine apparatus. Biopsies were analyzed for the extent, distribution and nature of any inflammatory infiltrate. We also observed for presence of any peri-eccrine fibrosis or other histologic changes that might hint at a prior inflammatory process.
Inflammation was scored from 0 to 4+. A score of "0" was given when less than 5 inflammatory cells were found in close proximity to the eccrine structures (<0.1 mm), score "1+" corresponded to 5 -25 inflammatory cells, "2+" similarly to 25 -40 inflammatory cells, "3+" to 40 -50 inflammatory cells and "4+" when more than 50 inflammatory cells were found in inflammatory infiltrate surrounding the sweat glands. We considered positive cases exhibiting "1+' and higher degree of inflammation.
To evaluate the composition of inflammatory infiltrate, we stained all positive specimens with CD4, CD20 and CD 138.
The control group included 31 random skin biopsies with no evidence of lupus erythematosus (LE), lichen striatus, Sjogren's syndrome or other diseases in which peri-eccrine infiltrate would be expected as a part of the disease process.

Results
Out of 84 eccrine structures 1+ inflammation was noted in 25, 2+ in 19, 3+ in 2, 4+ in 4 and no inflammation appeared to be in 34 structures (see Table 1). Table 1. Data from evaluation of eccrine structures according to study protocol (P -plasma cells, L -lymphocytes, EOS -eosinophils).  The inflammatory infiltrate in all positive biopsies was peri-ductal without involvement of the eccrine glandular structures. In all cases, the peri-ductular inflammation was localized at some distance from the primary pathology for which the biopsy was performed and was judged to be an independent an unrelated process (see Figure 1). Accompanied observations included peri-ductal eosinophils in 5 cases, peri-eccrine hemorrhage in 1 case and apoptotic keratinocytes in 2 eccrine ducts. Eosinophils were noted only in cases with higher degrees of inflammation and the presence of B -lymphocytes and plasma cells.
Overall, 60% of biopsies demonstrated some degree of inflammation related to the eccrine ducts. In contrast, all 31 skin biopsies in the control group showed less than five lymphocytes around the eccrine structures and were scored as "0" according to the criteria listed above. These symptoms are not routinely recognized or assessed for in SS patients and may be underestimated and commonly neglected [18,21]. To some measure, this is due to xerosis being perceived by clinicians as subjective and the fact that it is often associated with more attention demanding symptoms. This may also be attributed to a poor understanding of the mechanism of xerosis in SS patients. Herein, we demonstrated that most SS patients exhibit some degree of inflammation prior to developing any clinical cutaneous manifestations. These findings may play an important role in further understanding the pathophysiology of the disease in terms of its overall systemic nature, as well as the mechanism of disease progression, given the biological similarities between salivary and eccrine structures.

Discussion
There are scattered publications describing the histology of xerotic skin in SS patients.

CD20 CD138
A lymphocytic infiltrate was identified in 8 cases (66%). In addition to T lymphocytes, numerous B lymphocytes (marginal-zone-like and memory-type) were found within the inflammatory infiltrate surrounding eccrine ducts. Our findings correlate with data reported by the Roguedas' team, as well as these other studies. Additionally, we observed the composition of the inflammatory infiltrate to correlate with the degree of peri-eccrine inflammation. We demonstrated that T lymphocytes are the main components of the inflammatory infiltrate when inflammation is mild and the disease process is presumably in its initial stages, while increasing severity of inflammation is associated with presence of B-cells and plasma cells in the infiltrate. Therefore, it is possible to speculate that xerosis might result from immunologic destruction of the eccrine apparatus by an organized group of inflammatory cells with clearly defined roles for each member. It begins with T cells and leads to the production of antibodies by an erroneously selected and differentiated population of B cells. This process would be analogous to the destruction of salivary or lachrymal glands [25]. Considering exclusively T -lymphotropic qualities of the epidermis, it would be very unusual to locate B-or plasma cells in the peri-eccrine zone in asymptomatic skin unless for a reason. Chemotactic factors for B-cells are described in labial salivary glands [26] and might similarly be produced by all exocrine tissue [27]. The location of the inflammatory infiltrate in our study suggests these chemotactic factors might be, in theory, secreted by ductular epithelium rather than gland itself. Further studies are necessary to test the validity of this speculation.
Our study is the first histologic evaluation of asymptomatic skin in SS patients. We demonstrated the majority of these patients to have mild inflammation in the peri-eccrine zone. In five cases with higher degree of inflammation (according to study protocol) we noted presence of eosinophils. Although not striking in samples from asymptomatic patients, these cells might have a meaningful role when inflammation gets serious. Eosinophils might influence secondary destruction of the ducts. They are recruited via T cells and IL-5 and might also regulate local tissue remodeling and fibrosis [28].
The diagnosis of SS is based on histopathological examination of the minor salivary glands. The diagnostic finding includes an inflammatory infiltrate surrounding salivary and lacrimal glands and ducts that is primary composed of lymphocytes and plasma cells (mostly in lacrimal glands). Additional features are parenchymal atrophy as well as fibrosis, ductal ectasia and acute inflammation. The most characteristic feature of SS on biopsy is focal lymphocytic sialadenitis, with a sensitivity and specificity of >80% [29]. This is described as the presence of dense aggregates (foci) of ≥50 mononuclear cells (mostly lymphocytes), in a peri-ductal or perivascular localization [30]. In our study, cases with 4+ inflammation (2 cases -29 structures) met this criterion demonstrating a huge discordance in disease manifestation between minor salivary gland findings and cutaneous eccrine glands. This may mean that minor salivary glands might be more sensitive to the chronic inflammatory damage than eccrine glands and possibly have weaker abilities to self-repair. An appropriate grading scale for peri-eccrine inflammation and its prognostic or diagnostic significance must be determined with a larger study and long-term patient follow-up.
Obtaining skin samples from patients with suspected or established SS might be helpful for disease staging as well as evaluation of therapeutic measurements [24,31]. Since most of our cases revealed some degree of inflammation, we suggest that a majority of patients have subclinical cutaneous involvement at the time of the diagnosis. We support the idea to include skin biopsy in the routine care of SS. Evaluation of cutaneous exocrine glands might be particularly helpful in challenging situations i.e. symptomatic patients without identifiable sialadenitis etc. [32]. Skin biopsy could also serve as a secondary prognostic and diagnostic factor in those who simply decline lip biopsy because of cosmetic reasons.