Atypical Pseudonetworks in Pigmented Facial Macules: A Report of Two Cases

Special Article - Diagnosis and Usefulness of Dermoscopy

Austin J Dermatolog. 2017; 4(2): 1077.

Atypical Pseudonetworks in Pigmented Facial Macules: A Report of Two Cases

Kurita R, Yamamoto Y, Matsue H and Togawa Y*

Department of Dermatology, Chiba University of Graduate School of Medicine, Japan

*Corresponding author: Yaei Togawa, Department of Dermatology, Chiba University of Graduate School of Medicine, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8670, Japan

Received: September 11, 2017; Accepted: October 04, 2017; Published: October 11, 2017


We report two rare cases of a black facial macule showing atypical pseudonetwork on dermoscopy. Case 1 was a reticulated type of seborrheic keratosis and case 2 was a superficial Basal Cell Carcinoma (BCC). In general, pseudonetwork is seen in benign or malignant melanocytic lesions. Specifically, an atypical pseudonetwork is known as a hallmark of lentigo maligna and lentigo maligna melanoma. An atypical pseudonetwork is composed of four elements: asymmetrical pigmented follicular openings, rhomboidal structures, annular granular structures, and a gray pseudonetwork. We found no case report of a reticulated-type seborrheic keratosis showing asymmetric pigmented follicular openings with a dark brown rim, as was seen in our case. Furthermore, reticular lines including a pigment network and pseudonetwork are important features, excluding pigmented BCC, and only one case of superficial BCC with an atypical pseudonetwork has been reported. In Case 2, pseudonetwork made of blue-gray network-like pigmentation on pink whitish structureless areas could be seen. It is important to know the diagnostic pitfalls of non-melanocytic pseudonetwork on dermoscopy, although it has useful features for diagnosis of facial pigmented lesions.

Keywords: Atypical pseudonetwork; Basal cell carcinoma; Dermoscopy; Lentigo maligna; Lentigo maligna melanoma; Seborrheic keratosis

Case Presentation

Lentigo Maligna (LM) or Lentigo Maligna Melanoma (LMM) is a type of melanoma that appears predominantly on the face and sun-exposed areas, as large pigmented macules. The presence of a facial atypical pseudonetwork on dermoscopy has been reported to be one of the most important diagnostic clues for LM or LMM [1]. However, with pseudonetwork it is sometimes difficult to distinguish between benign and not benign, as well as between melanocytic or not melanocytic features. Here, we report two cases with a pigmented facial macule with an atypical pseudonetwork that can help to differentiate it from melanoma.

Case 1

An 81-year-old female patient presented with a lesion on her right cheek that appeared 10 years ago. Upon clinical examination, it appeared as a brown macule with multiple shades of maroon, measuring 10 x 8mm (Figure 1A). Dermoscopic examination revealed a brown structureless area free of hair follicles that formed a pseudonetwork with a sharp border (Figure 1B). The pseudonetwork seemed to be atypical, because some asymmetric pigmented follicular openings also could be seen in the lesion as a hyperpigmented rim. Moreover, in the 4 o’clock area of the border, there was an eccentric darker brown pseudonetwork. We hypothesized that the lesion was a solar lentigo because of its structureless area and sharp border. However, we could not rule out LMM completely. We performed a histologic examination of the center of the lesion and of the eccentric pigmented border of the lesion. In the center of the lesion, tumor nests with melanin infiltrated into the upper dermis from the basal layer of the flat epidermis. The tumor nests had two layers of basaloid cells containing melanin that avoided the hair follicles, although they showed uneven melanosis around the follicles (Figure 2A). In the eccentric darker area on the border, tumor nests infiltrated deeper into the dermis and coalesced with each other (Figure 2B). The tumor nests were made of basaloid cells arranged in articulated pattern, and some pseudohorn cysts were also seen. Finally, we diagnosed the lesion as an early stage of reticulated-type seborrheic keratosis.