Expression of p40 in Primary Cutaneous Mucinous Carcinoma Versus Primary Mucinous Carcinomas of the Breast and Colon

Primary Mucinous Carcinoma of Skin: A Rare Cutaneous Neoplasm. Clinicopathologic Features, Differential Diagnoses, and Review of Literature

ABSTRACT

Primary mucinous carcinoma of the skin (PMCS) is a rare malignant neoplasm of sweat gland origin, with an incidence of 0.07 per million. Histologically, it may be difficult to differentiate it from metastatic mucinous carcinomas of the skin. A case of PMCS is reported here in a 59-year-old woman who presented with a lesion on the right lower eyelid. Histological examination revealed features of mucinous adenocarcinoma. The main differential diagnosis was metastatic mucinous adenocarcinoma; however, the lack of colorectal and lung markers and the presence of focal in situ components were consistent with the diagnosis of PMCS. PMCS and breast mucinous carcinoma share immunohistochemical markers, such as GCDFP-15 and mammaglobin; however, focal in situ component with the presence of myoepithelial cells in the tumor ruled out metastatic mucinous carcinoma of breast origin. The subsequent mammograms did not reveal any breast lesions. Colonoscopy did not show any evidence of colonic malignancy, and imaging studies (CT scan) did not show any evidence of neoplasm in the body. These findings were in keeping with a diagnosis of PMCS. The present case emphasizes the importance of clinicopathological correlation, histopathology, and immunohistochemistry in the accurate diagnosis of PMCS and summarizes the literature on these rare cutaneous neoplasms.

Primary cutaneous mucinous carcinoma of the scalp masquerading as a benign dermatological mass - A case report

INTRODUCTION AND IMPORTANCE

Primary cutaneous mucinous carcinoma (PCMC) is a rare low-grade malignant neoplasm derived from the sweat glands. Local recurrence of PCMC occurs frequently, but these lesions rarely metastasize. Due to the absence of classical demographic and clinical characteristics, PCMCs masquerade as sebaceous cyst, lipoma, pilomatrixoma, chalazion, or squamous cell carcinoma. This misdiagnosis frequently leads to incomplete surgical excision which necessitates further surgical therapy for a curative intent.

CASE PRESENTATION

We present a case of PCMC in a 45-year-old woman which presented as a slow- growing and symptomless nodule in the scalp. After clinical evaluation, the patient had a typical surgical excision for a benign-looking lesion. Histological evaluation of the specimen confirmed a localized PCMC in the scalp with involved surgical margins.

CLINICAL DISCUSSION

A thorough oncological assessment by PET-CT scan and radionuclide scintigraphy was performed. Later, a wide local excision using a gamma probe for intra-operative radionuclide localization of the tumor area and sentinel lymph nodes was done.

CONCLUSION

The patient did not have any regional or distant metastases and remained stable at the time of reporting this case.

Primary Cutaneous Mucinous Carcinoma: A Review of the Literature

BACKGROUND

Primary cutaneous mucinous carcinoma (PCMC) is an exceedingly rare, low-grade tumor that histologically resembles mucinous carcinoma from other primary sites, such as the breast, gastrointestinal tract, and lungs.

OBJECTIVE

The purpose of this article was to review the current literature on PCMC as it relates to epidemiology, clinical presentation, histopathology, immunohistochemistry, treatment, and prognosis.

MATERIALS AND METHODS

An extensive literature review was conducted using PubMed and Ovid MEDLINE to identify articles related to PCMC.

RESULTS

Several hundred cases have been reported in the medical literature, and surgical resection, whenever feasible, is the standard of care.

CONCLUSION

The diagnosis of primary cutaneous mucinous carcinoma is one of exclusion, requiring a metastatic work-up to rule out distant primary. Mohs micrographic surgery is a tissue sparing technique that allows complete margin control of these rare neoplasia.

Primary mucoepidermoid carcinoma of the external auditory canal with a CRTC1::MAML2 fusion: A case report and a review of literature

Mucoepidermoid carcinoma is a malignant neoplasm of exocrine glands that arises predominantly in salivary glands. It is seldom encountered as a primary cutaneous neoplasm, and in those patients, it often involves the external auditory canal. Given their rarity, they can pose a diagnostic challenge and prompt extensive workup. In salivary glands, mucoepidermoid carcinomas commonly harbor CRTC1/3::MAML2 fusions; however, genetic alterations of primary cutaneous neoplasms are less characterized, with previous studies reporting CRTC1 rearrangements in the absence of MAML2 aberrations. Herein, we report a case of a primary cutaneous mucoepidermoid carcinoma of the external auditory canal with a CRTC1::MAML2 rearrangement. We also review the clinical, morphologic, and molecular features of this neoplasm and compare them to those reported in the literature and to histopathologic mimics.

TRPS1, a New Promising Marker for Assessment of Distant Metastatic Breast Cancer

This article reviewed the identification of breast cancer in the distant metastatic setting through traditional immunohistochemical markers, such as mammaglobin and GATA3, compared with the novel immunohistochemical stain, Trichorhinophalangeal syndrome-1 (TRPS1). We review previous studies evaluating TRPS1 staining, which were conducted using cytology specimens, as well as our recently conducted study evaluating this stain using surgical tissue samples, both from primary and distant metastatic invasive breast carcinoma. In summary, although no immunohistochemical stain is 100% specific or sensitive, in the metastatic setting where tissue available for ancillary studies is limited, TRPS1 was a reliable and even a standalone marker for breast origin, particularly in cases of triple-negative breast cancer.

Cutaneous Neuroendocrine Mucinous Carcinomas Are Low-grade But May Be Associated With Other Cancers

Primary cutaneous mucinous sweat gland carcinoma is said to be prognostically stratifiable by neuroendocrine differentiation, however, this assertion is based on historical data and older staining techniques. We aimed to evaluate the percentage of mucinous and nonmucinous adnexal tumors expressing the newer, more sensitive neuroendocrine marker insulinoma-associated protein 1 (INSM1), and to assess clinicopathologic features in patients cohorted by this phenotype. Of 12 available adnexal/cutaneous adenocarcinomas, 9 were mucinous, 3/9 of which were INSM1-negative, and 2/3 with nodal metastases. Of 3 nonmucinous cases, all were INSM1-negative, 1/3 with nodal metastasis, and 2/3 with lymphovascular invasion. In contrast, of 6 mucinous INSM1-positive cases, no cases had LVI or metastasis, however, 3 patients died during follow-up, 2 from breast or urothelial cancer. A fourth patient developed breast carcinoma. INSM1-positive tumors, from cheek (3), scalp (2), and chin (1) were estrogen receptor and progesterone receptor positive. No cases of apocrine adenoma or hidrocystoma, basal cell, or sebaceous carcinoma labeled with INSM1. While most primary cutaneous mucinous carcinomas are of the neuroendocrine type, our study confirms the presence of occasional non-neuroendocrine mucinous carcinomas. We validate the association of such tumors and nonmucinous non-neuroendocrine adnexal carcinoma with intermediate-grade behavior, including lymph node metastases, but not death. Conversely, neuroendocrine expressing primary cutaneous mucinous carcinoma may represent the well-differentiated neuroendocrine neoplasm/neuroendocrine tumor primary to skin, with low-grade behavior, but attendant risk of germline susceptibility to other aggressive extracutaneous tumors. Routine assessment of cutaneous adnexal carcinoma with INSM1 and longer term follow-up and cancer screening of patients with positive staining is recommended.

Recurrent Neuroendocrine Primary Cutaneous Mucinous Carcinoma of the Scalp After Complete Excision

ABSTRACT

Primary cutaneous mucinous carcinoma is a rare, indolent malignancy with a debated history regarding cell of origin. Recurrence is rare but has been documented in up to a third of cases. Recent literature reviews have recognized 2 possible subtypes-neuroendocrine and nonneuroendocrine- with different possible prognostic implications for patients. We describe a case of recurrent primary cutaneous mucinous carcinoma in a 50-year-old man with subtle neuroendocrine features not initially recognized on routine H&E staining but highlighted by immunohistochemical studies. We underscore the importance of immunohistochemical use in these rare cases and emphasize that awareness of these neuroendocrine and nonneuroendocrine subtypes is essential for a complete diagnosis.