A Case of Pagetoid Bowen's Disease.

To the Editor: A 65-year-old woman presented with a cutaneous red-brown plaque on the left posterior thigh for the past 7 years. Initially, the lesion was a slightly elevated, well-demarcated plaque with a smooth surface and was about 1 cm in diameter, without any symptoms. Over the years, it slowly extended into an elevated plaque with rough surface, frequently bleeding after slight friction. Physical examination revealed an obviously elevated, well-demarcated red-brown plaque (3.0 cm × 2.7 cm) covered by crusts on the left posterior thigh [Figure 1a], with slightly tenderness. Biopsy showed hyperkeratosis and parakeratosis. Acanthosis with irregular elongation of the rete ridges was in the involved epidermis [Figure 1b]. There were clear cells (some contained large cytologically atypical nuclei stained dark) [Figure 1c] in the stratum spinosum, and the basement membrane was not involved. Immunohistochemical findings revealed negative for PAS [Figure 1d], S100, HMB-45, CEA, and GCDFP15 [Figure 1e], positive for Ki-67 (<30%), CK34βE12 [Figure 1f], and P63 [Figure 1g], and weakly positive for CAM5.2 [Figure 1h]. The diagnosis of pagetoid Bowen's disease (BD) is definite. Later, a wide local excision (1.0 cm margin) was performed with negative margins of resection. Among all the histological variants of BD, pagetoid BD has been reported to occur in only 4.6% of BD. Unlike typical BD, pagetoid BD commonly presents in the upper and lower extremities, followed by head/neck and trunk area, with very rare cases appearing in the external genitalia location.[1] In this case, the lesion first appeared to be nevoid, suggesting that it might be secondary to a preexisting nevocellular nevus. It is also reported that a few cases of classic BD arise in the preexisting skin lesions such as seborrheic keratosis.[2] Histologically, pagetoid BD is characterized by nests of atypical keratinocytes with round nuclei and abundant pale cytoplasm located either singularly or in groups within the epidermis, and the main differential diagnosis of pagetoid cells includes extra-mammary pagetoid disease (EMPD) and malignant melanoma in situ (MIS). Similar to classic BD, pagetoid BD always shows full-level involvement of the epidermis, scattered multinucleated tumor giant cells, keratohyalin granules, single-cell keratinization, and intercellular bridges visible between pagetoid cells, while EMPD lesion contains pagetoid cells well demarcated from nearby epidermal cells, flattened basal layer, stratum corneum involved, acinar structures, and no intercellular bridge. Well-demarcated pagetoid cells and stratum corneum involved can occur in MIS lesion; in contrast, follicular extension shows up in MIS only. Immunohistochemical tests are always helpful. The melanocytic markers such as S100, melan-A, and HMB-45 show great value in distinguishing MIS from pagetoid BD as only MIS lesions tend to be stained positive. CK34βE12 shows that the cells may stem from keratinocyte. CEA and GCDFP15 illustrate that the cells are probably from sweat glands. CAM5.2 and Ber-EP4 are generally considered to support the diagnosis of EMPD;[3] however, some cases of pagetoid BD show positive for them.[4] Recent studies suggest that p63 might be a useful marker as it stains atypical keratinocytes of BD but not EMPDs.[5] This patient's tissue [Supplementary Table 1] shows positive for P63, Ki-67 (<30%), and CK34βE12, weakly positive for CAM5.2, and negative for PAS, S100, HMB-45, CEA, and GCDFP15. Based on these findings, MIS and EMPD can be excluded; a diagnosis of pagetoid BD was confirmed.

Figure 1

(a) The elevated, well-demarcated red-brown lesion with crusts on the left thigh. (b) Nests of atypical keratinocytes within the epidermis, as well as hyperkeratosis, parakeratosis, and acanthosis (H and E, original magnification ×50). (c) Large clear cells with pale-staining cytoplasm (H and E, original magnification ×400). (d) Atypical cells showed negative staining with PAS (original magnification ×200). (e) The pagetoid cells show negative for GCDFP15 (original magnification ×100). (f) The pagetoid cells are uniformly positive for CK34βE12 (original magnification ×100). (g) The pagetoid cells show strong nuclear positive for P63 (original magnification ×100). (h) The pagetoid cells show weakly positive for CAM5.2 (original magnification ×100).

Supplementary Table 1

Immunohistochemical results in pagetoid BD, EMPD, and MIS

Antibody reagent	Pagetoid BD	EMPD	MIS
PAS	–	+	–
S100	–	–	+
HMB-45	–	–	+
Melan-A	–	–	+
CEA	–	+	–
GCDFP15	–	+	–
Ki-67	+ (<30%)	–	+
CK34βE12	+	–	–
P63	+	–	–
CAM5.2	±	+	–

EMPD: Extra-mammary pagetoid disease; BD: Bowen’s disease; MIS: Malignant melanoma in situ. –: Negative; +: Positive; ±: Weakly positive.

Supplementary information is linked to the online version of the paper on the Chinese Medical Journal website.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initial will not be published and efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This work was supported by grants from the National Natural Science Foundation of China (No. 81371731) and the Milstein Medical Asian American Partnership Foundation.

Conflicts of interest

There are no conflicts of interest.