Microcystic adnexal carcinoma with germinative follicular differentiation

Microcystic adnexal carcinoma of the eyelid and orbit: A case report and review of literature

Microcystic adnexal carcinoma (MAC), a rare and low-grade malignant skin tumor, is characterized by a high rate of misdiagnosis and a preponderance for local recurrence, but seldom seen nodal or distant metastasis. Although MAC typically occurs almost in the head and neck region, primary eyelid or orbital MAC is very rare. To explore the unique characteristics of the eyelid and orbital MAC, we reviewed the relevant literature. Based on its distinctive anatomical location and the aggressive behavior, eyelid or orbital MAC not only exhibit a high rate of misdiagnosis and local recurrence, but also lead to serious complications such as disfigurement after orbital exenteration, paranasal sinuses or intracranial invasion, even death. Misdiagnosis of MAC commonly result from its rarity and nonspecific clinical and histopathological presentation. To reduce or avoid misdiagnosis, it is important to increase awareness for MAC and obtain a full-thickness biopsy specimen in histopathological analysis. Due to its extensive invasive growth pattern, MAC has a high rate of local recurrence, so complete excision with clear margins and long-term follow-up of patients with MAC are necessary. About those serious complications of the eyelid and orbital MAC, early and accurate diagnosis, complete excision is very important. Moreover, an interprofessional team consisting of ophthalmologist, otolaryngologist, neurologist, dermatologist, pathologist, radiologist is needed to evaluate and treat this disease. In summary, increasing awareness, early and accurate diagnosis, complete excision, long-term follow-up, and a multidisciplinary team is crucial for management of the eyelid and orbital MAC.

Microcystic Adnexal Adenoma: The Benign Counterpart of Microcystic Adnexal Carcinoma

ABSTRACT

Microcystic adnexal carcinoma (MAC) is a low-grade malignant neoplasm of slow growth and low metastatic potential, but locally aggressive. Architecturally, MAC is usually a poorly circumscribed neoplasm that tends to extend deeply into the dermis and subcutaneous tissue. We present here a lesion in which the histopathologic study showed a well-demarcated nodular lesion involving the mid dermis and composed of small cystic keratinous structures, solid aggregates of pale squamous cells without cytologic atypia and ductal structures. Although these neoplastic components resembled those of MAC, the sharp delimitation of the lesion as well as the absence of deep extension and perineural involvement supported the benign nature of this lesion. We have named this neoplasm microcystic adnexal adenoma, as the benign counterpart of MAC.

Expression of Hedgehog signalling molecules in microcystic adnexal carcinoma

BACKGROUND

Microcystic adnexal carcinoma (MAC) is a rare skin neoplasm that has not been characterized on a molecular basis.

AIM

To assess expression profiles of Hedgehog (HH) signalling molecules in MAC and control tumours.

METHODS

Immunohistochemistry was performed for Sonic Hedgehog (SHH), Indian Hedgehog (IHH), Patched 1 (PTCH1) and Smoothened (SMO) on patient MAC tissue (n = 26) and control tumour tissue, including syringoma (SyG; n = 11), trichoepithelioma (TE; n = 11) and basal cell carcinoma (BCC; n = 12) tissues.

RESULTS

Patched 1 and SMO immunoreactivity was significantly higher in BCC than in SyG, TE or MAC (P < 0.001 and P < 0.03, respectively). The highest IHH expression was observed in BCC and TE compared with SyG and MAC (P < 0.04). Notably, the highest SHH protein expression was observed in SyG compared with MAC, TE and even BCC (P < 0.001). In patients with MAC, SMO immunoreactivity significantly (r = 0.51; P < 0.01) correlated with PTCH1 expression. Further correlation studies did not show significant associations between the HH expression markers assessed (P > 0.05).

CONCLUSION

Our results indicate that alterations of the HH signalling are unlikely to play a major role in the pathogenesis of MAC, which is in contrast to the morphologically similar BCC and TE. Our observation provides additional information to the limited molecular pathology knowledge on this rare tumour.