Differentiating between squamous cell carcinoma and pigmented squamous cell carcinoma.

An 82-year-old man presented to the otolaryngology clinic for excision of a lesion on the helix of his left ear. His history was significant only for multiple excisions of basal cell carcinomas, squamous cell carcinomas, and other dysplastic lesions of the skin. The helical lesion was approximately 1.5 cm wide, and it had a 3- to 4-mm pigmented, ulcerated center with raised edges underneath a scab. The lesion was completely excised with clear margins, and it was diagnosed as a pigmented squamous cell carcinoma (pSCC).

The pigmented subtype of SCC is exceedingly rare; pSCC is estimated to account for only 0.01% of all SCCs. When it does occur, it usually arises in the oral cavity and conjunctiva; case reports have documented a variety of other locations, including the uterine cervix, scrotum, skin, external auditory canal, and nasal cavity. (1-9) Cutaneous pSCC is often described as a rapidly growing crusted papule on actinic damaged skin. (1)

Although pSCC contains squamous cells with features typical of SCC (e.g., intracellular bridges, keratin pearls, and reactivity to markers for high-molecular-weight keratin), it is also made up of melanin-containing cells. These pigmented cells include melanophages and cells that show squamous differentiation (figure, A). Dendritic cells reactive for S-100 protein are also interspersed within the tumor (figure, B).

[FIGURES A-B OMITTED]

Despite histopathologic differences, the prognosis of pSCC is reportedly similar to that of SCC. (1) Awareness and recognition of pSCC are important because it can be confused with a melanoma, which has a more ominous prognosis.

References

(1.) Morgan MB, Lima-Maribona J, Miller RA, et al. Pigmented squamous cell carcinoma of the skin: Morphologic and immunohistochemical study of five cases. J Cutan Patho12000;27:381-6.

(2.) Masuzawa N, Kishimoto M, Takahashi Y. Pigmented squamous cell carcinoma of the uterine cervix. Int J Gynecol Patho1 2003;22: 285-8.

(3.) Shields JA, Shields CL, Eagle RC Jr, et al. Pigmented conjunctival squamous cell carcinoma simulating a conjunctival melanoma. Am J Ophthalmo1 2001; 132:104-6.

(4.) Chapman MS, Quitadamo MJ, Perry AE. Pigmented squamous cell carcinoma. J Cutan Pathol 2000;27:93-5.

(5.) Matsumoto M, Sonobe H, Takeuchi T, et al. Pigmented squamous cell carcinoma of the scrotum associated with a lentigo. Br J Dermatol 1999; 141:132-6.

(6.) Kamiya M, Maehara R, Iizuka S, et al. Pigmented squamous cell carcinoma with dendritic melanocyte colonization in the external auditory canal. Pathol Int 1998;49:909-12.

(7.) Jurado I, Saez A, Luelmo J, et al. Pigmented squamous cell carcinoma of the skin: Report of two cases and review of the literature. Am J Dermatopathol 1999;20:578-81.

(8.) Mathews A, Abrabam E, Amman S, Nair MK. Pigmented squamous cell carcinoma of nasal cavity. Histopathology 1998;33:184-5.

(9.) Kuwabara H, Uda H, Miyaguchi M, et al. Pigmented squamous cell carcinoma of the alveolar ridge in the oral mucosa. Oral Surg Oral Med Oral Pathol 1994;77:61-5.

From the Division of Otolaryngology-Head and Neck Surgery, Duke University Medical Center, Durham, N.C. (Dr. Chang); and the Department of Pathology (Dr. Chapman) and the Division of Otolaryngology-Head and Neck Surgery (Dr. Furdyna), Asheville (N.C.) Veterans Administration Medical Center.

Christopher Y. Chang, MD; William E. Chapman, MD; Julia A. Furdyna, MD