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Tumor Discovery Aggressive sebaceous carcinoma of the scalp

pathogenic germline variants of DNA mismatch repair Clear cell squamous cell carcinoma, on the other
genes MSH2, MSH6, and MLH1 have been identified in 8 – hand, shows clear cells; however, their cytoplasm is
29% of individuals with SC . In these patients, the tumors not as multivacuolated as sebocytes. Without lobular
[7]
are characterized by microsatellite instability. arrangement, it is difficult to determine sebaceous
[11]
On microscopy, sebaceous neoplasm shows a wide differentiation in squamous cell carcinoma .
range of differentiation: Sebaceous adenoma, basal cell On immunohistochemistry, SC tumor cells are reactive
carcinoma with sebaceous differentiation, and sebaceous for epithelial membrane antigen (EMA), cytokeratin,
carcinoma . In SC, the tumor cells are arranged in cords Ber-EP4, and adipophilin (adipose differentiation-related
[8]
and lobules, the neoplastic cells show varying degrees of protein, ADP), which has a membranous vesicular pattern,
sebaceous differentiation, and there is tumor infiltration to and androgen receptor . Androgen receptors and ADPs
[12]
adjacent soft tissue, nerve, or the lymphatic system. Less are not observed in squamous cell carcinoma, but EMA,
commonly, it exhibits a broad superficial intraepidermal cancer antigen (CA)15-3, Ber-EP4, and ADP are observed
pattern. in basal cell carcinoma, thus differentiating them from SC.
The architecture usually consists of sheets or lobules Immunohistochemistry can also be used to evaluate MSH2,
separated by fibrovascular stroma. The various histologic MSH6, MLH1, and PMS2 for microsatellite instability in
patterns of SC include lobular, cystic with the central SC, as SC may metastasize in 2.4% of cases. According
comedo-type necrosis, papillary, and mixed type. The to the literature, local recurrence is more common in
[12]
atypical sebocytes may be well, moderately, or poorly extraocular SC .
differentiated. They are arranged as rounded nodular One of the features that is indicative of poor prognosis
aggregates or angulated infiltrative aggregates. A well- is tumor size >1 cm (associated with a 5-year mortality
differentiated SC shows increased proportion of mature rate of 50%). The other features include moderate-to-
appearing multivacuolated sebocytes with nuclear poor sebaceous differentiation, tumor necrosis, increased
indentation, mild nuclear pleomorphism, and minimal mitotic activity, infiltrative growth, and lymphovascular
mitoses and necrosis. In contrast, anaplastic cells, with invasion.
prominent nuclear pleomorphism and frequent mitoses For local disease, wide local excision is the preferred
and necrosis, are observed in moderate to poorly
differentiated SC. In terms of tumor dissemination, these treatment. Other modalities of treatment include
Mohs micrographic surgery, radiation, and systemic
tumors may occasionally spread in a pagetoid manner . chemotherapy, which may be considered for recurrent or
[9]
Tumor multicentricity, differentiation, pagetoid spread, metastatic disease .
[13]
and perineural, vascular, and lymphatic invasion should
be emphasized in pathological reporting since this Bailet et al. have reported a local recurrence rate of 29%,
information can aid clinicians in treating patients with SC. regional nodal metastasis in 15%, and a disease-related
mortality of 20% . It has also been reported that the 5-year
[9]
Sebaceous adenoma, basal cell carcinoma with
sebaceous differentiation, clear cell melanoma, clear cell survival rate of this SC is 92.7%. SC is primarily treated
with wide local excision, and in cases of localized tumor,
squamous cell carcinoma, clear cell hidradenocarcinoma,
metastatic renal cell carcinoma, and prostate carcinoma the prognosis is good following surgical removal. However,
are among the benign and malignant conditions that are in scalp SC, adjuvant treatment with radiation and
considered differential diagnoses for SC . chemotherapy is required. A study conducted by Angela
[10]
Orcurto et al. noted the recurrence of aggressive SC of the
Sebaceous adenoma is a benign epithelial neoplasm scalp even after multiple excisions and local radiotherapy .
[14]
with hyperplasia of sebaceous lobules associated with In another study, Bhavaraju noted aggressive SC over the
expansive aggregates of basaloid germinative cells. It is a scalp and suggested the need for close follow-up of these
well circumscribed neoplasm that principally demonstrates patients to detect recurrence and distant metastasis .
[15]
organoid and lobular configuration and contains a significant In our case, the patient was asymptomatic without any
percentage of mature and lipid-rich sebaceous cells. evidence of locoregional recurrence on follow-up.
Another differential is basal cell carcinoma with
sebaceous differentiation. Its tumor cells are small basaloid 4. Conclusion
with peripheral palisading, surrounded by fibromyxoid Extraocular SC is an aggressive malignant neoplasm of the
stroma, with focal differentiation toward mature, benign- skin. The management of SC is challenging and patient
appearing, and multivacuolated sebocytes. In contrast, assessment may be necessary depending on the prognostic
there is no peripheral palisading in SC. features. We present a case of SC of the scalp along with

Volume 1 Issue 2 (2022) 3 https://doi.org/10.36922/td.v1i2.203