Purpose:
The purpose of this study is to describe the characteristics of mucin-producing sweat gland carcinoma (MPSGC) and to determine whether endocrine differentiation is of prognostic significance.
Methods:
The medical records of all patients diagnosed with MPSGC between 1990 and 2011 at the New York Eye and Ear Infirmary were reviewed. Clinical data collected included patient demographics, tumor location and appearance, adequacy of surgical excision, recurrence and metastasis. Histopathology and immunohistochemistry were reviewed, including tumor morphology, in-situ vs. invasive distribution (based in part on immunostaining for myoepithelial markers smooth muscle actin and p63), evidence of apocrine differentiation (BRST-2, estrogen and progesterone receptors), mitotic index (ki-67), and neuroendocrine differentiation (neuron-specific enolase, synaptophysin, chromogranin and CD56).
Results:
15 eyes of 15 patients were identified. The mean age at diagnosis was 70 years (range 53-87), with 66% (10/15) male and 33% (5/15) female patients. Forty seven percent (7/15) of lesions were located on the lower lid and 53% (8/15) on the upped lid. All tumors were excised initially with positive margins. Re-excision for margin clearance was performed in 5/15 cases. The mean follow-up period was 20 months (range 4 days - 82 months).Histopathologic and immunohistochemical evaluation showed that 33% (5/15) of tumors were in situ, 40% (6/15) invasive, and 27% (4/15) demonstrated both growth patterns. All tumors showed apocrine differentiation and had ki-67 proliferative index of 3-5%. All tumors showed focal positivity for at least 1 of the 4 neuroendocrine markers.Recurrence was noted in two lesions--one with an in situ component and one with an invasive component--at 3 years and at 10 months respectively, despite pathologically confirmed clearance of surgical margins. Recurrent tumors had histopathologic and immunohistochemical characteristics identical to the primary lesion. None of the patients developed regional or distal metastases.
Conclusions:
MPSGC is a rare tumor which pathologically presents as a continuum, from an in situ lesion with hydrocystoma-like appearance to classic, invasive carcinoma nests floating in pools of mucin. An invasive component is not necessary for recurrence to occur and all cases of MPSGC should be closely monitored for the possibility of recurrence. Endocrine differentiation can be observed in all lesions and does not appear to have a prognostic significance, arguing against the utility of immunohistochemical sub-typing of MPSGC.
Keywords: eyelid • immunohistochemistry • CAR